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Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2016	Feb. 21, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	HELIX ENERGY SOLUTIONS GROUP INC
Entity Central Index Key	0000866829
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		147,660,932
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 707.1

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 356,647	$ 494,192
Accounts receivable:
Trade, net of allowance for uncollectible accounts of $1,778 and $350, respectively	101,825	76,287
Unbilled revenue and other	10,328	20,465
Current deferred tax assets	16,594	53,573
Other current assets	37,388	39,518
Total current assets	522,782	684,035
Property and equipment	2,450,890	2,544,857
Less accumulated depreciation	(799,280)	(941,848)
Property and equipment, net	1,651,610	1,603,009
Other assets:
Equity investments	0	26,200
Goodwill	0	45,107
Other assets, net	72,549	41,608
Total assets	2,246,941	2,399,959
Current liabilities:
Accounts payable	60,210	65,370
Accrued liabilities	58,614	71,641
Income tax payable	0	2,261
Current maturities of long-term debt	67,571	71,640
Total current liabilities	186,395	210,912
Long-term debt	558,396	677,695
Deferred tax liabilities	167,351	180,974
Other non-current liabilities	52,985	51,415
Total liabilities	965,127	1,120,996
Commitments and contingencies
Shareholders’ equity:
Common stock, no par, 240,000 shares authorized, 120,630 and 106,289 shares issued, respectively	1,055,934	945,565
Retained earnings	322,854	404,299
Accumulated other comprehensive loss	(96,974)	(70,901)
Total shareholders’ equity	1,281,814	1,278,963
Total liabilities and shareholders’ equity	$ 2,246,941	$ 2,399,959

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Allowance for uncollectible accounts	$ 1,778	$ 350
Shareholders’ equity:
Common stock, shares authorized	240,000,000	240,000,000
Common stock, shares issued	120,630,000	106,289,000

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Net revenues	$ 487,582	$ 695,802	$ 1,107,156
Cost of sales:
Cost of sales	441,066	584,566	763,120
Asset impairments	0	345,010	0
Total cost of sales	441,066	929,576	763,120
Gross profit (loss)	46,516	(233,774)	344,036
Goodwill impairments	(45,107)	(16,399)	0
Gain on disposition of assets, net	1,290	92	10,240
Selling, general and administrative expenses	(65,934)	(57,279)	(92,520)
Income (loss) from operations	(63,235)	(307,360)	261,756
Equity in earnings (losses) of investments	(2,166)	(124,345)	879
Net interest expense	(31,239)	(26,914)	(17,859)
Loss on repurchase of long-term debt	(3,540)	0	0
Other income (expense), net	3,510	(24,310)	814
Other income – oil and gas	2,755	4,759	16,931
Income (loss) before income taxes	(93,915)	(478,170)	262,521
Income tax provision (benefit)	(12,470)	(101,190)	66,971
Net income (loss), including noncontrolling interests	(81,445)	(376,980)	195,550
Less net income applicable to noncontrolling interests	0	0	(503)
Net income (loss) applicable to common shareholders	$ (81,445)	$ (376,980)	$ 195,047
Earnings (loss) per share of common stock (in dollars per share)
Basic	$ (0.73)	$ (3.58)	$ 1.85
Diluted	$ (0.73)	$ (3.58)	$ 1.85
Weighted average common shares outstanding (in shares)
Basic	111,612	105,416	105,029
Diluted	111,612	105,416	105,045

Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss), including noncontrolling interests	$ (81,445)	$ (376,980)	$ 195,550
Other comprehensive loss, net of tax:
Unrealized gain (loss) on hedges arising during the period	2,366	(25,259)	(37,364)
Reclassification adjustments for loss on hedges included in net income (loss)	12,851	13,659	3,365
Reclassification adjustments for loss from derivative instruments de-designated as cash flow hedges included in net loss	0	18,014	0
Income taxes on unrealized (gain) loss on hedges	(5,347)	(2,214)	11,899
Unrealized gain (loss) on hedges, net of tax	9,870	4,200	(22,100)
Foreign currency translation loss arising during the period	(33,899)	(12,849)	(19,464)
Reclassification adjustment for net translation gain realized upon liquidation	(2,044)	0	0
Foreign currency translation loss	(35,943)	(12,849)	(19,464)
Other comprehensive loss, net of tax	(26,073)	(8,649)	(41,564)
Comprehensive income (loss)	(107,518)	(385,629)	153,986
Less comprehensive income applicable to noncontrolling interests	0	0	(503)
Comprehensive income (loss) applicable to common shareholders	$ (107,518)	$ (385,629)	$ 153,483

Consolidated Statements Of Shareholders' Equity - USD ($) $ in Thousands	Total	Total Controlling Interest Shareholders' Equity [Member]	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]
Balance, beginning of period at Dec. 31, 2013	$ 1,524,110	$ 1,499,051	$ 933,507	$ 586,232	$ (20,688)	$ 25,059
Balance, beginning of period (in shares) at Dec. 31, 2013			105,640,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	195,550	195,047		195,047		503
Foreign currency translation adjustments	(19,464)	(19,464)			(19,464)
Unrealized gain (loss) on hedges, net	(22,100)	(22,100)			(22,100)
Distributions to noncontrolling interests	(1,018)					(1,018)
Acquisition of noncontrolling interests	(21,646)	2,898	$ 2,898			(24,544)
Stock repurchases	(7,698)	(7,698)	$ (7,698)
Stock repurchases (in shares)			(321,000)
Activity in company stock plans, net and other	3,496	3,496	$ 3,496
Activity in company stock plans, net and other (in shares)			267,000
Share-based compensation	2,176	2,176	$ 2,176
Excess tax from share-based compensation	68	68	68
Balance, end of period at Dec. 31, 2014	1,653,474	1,653,474	$ 934,447	781,279	(62,252)	0
Balance, end of period (in shares) at Dec. 31, 2014			105,586,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(376,980)	(376,980)		(376,980)
Foreign currency translation adjustments	(12,849)	(12,849)			(12,849)
Unrealized gain (loss) on hedges, net	4,200	4,200			4,200
Activity in company stock plans, net and other	3,443	3,443	$ 3,443
Activity in company stock plans, net and other (in shares)			703,000
Share-based compensation	5,463	5,463	$ 5,463
Cumulative share-based compensation in excess of fair value of modified liability awards	2,915	2,915	2,915
Excess tax from share-based compensation	(703)	(703)	(703)
Balance, end of period at Dec. 31, 2015	1,278,963	1,278,963	$ 945,565	404,299	(70,901)	0
Balance, end of period (in shares) at Dec. 31, 2015			106,289,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(81,445)	(81,445)		(81,445)
Foreign currency translation adjustments	(35,943)	(35,943)			(35,943)
Unrealized gain (loss) on hedges, net	9,870	9,870			9,870
Equity component of debt discount on Convertible Senior Notes due 2022	10,719	10,719	$ 10,719
Re-acquisition of equity component of debt discount on Convertible Senior Notes due 2032	$ (1,625)	(1,625)	(1,625)
Stock repurchases (in shares)	(3,589,425)
Issuance of common stock, net of transaction costs	$ 96,547	96,547	$ 96,547
Issuance of common stock, net of transaction costs (in shares)			13,019,000
Activity in company stock plans, net and other	463	463	$ 463
Activity in company stock plans, net and other (in shares)			1,322,000
Share-based compensation	5,767	5,767	$ 5,767
Cumulative share-based compensation in excess of fair value of modified liability awards	203	203	203
Excess tax from share-based compensation	(1,705)	(1,705)	(1,705)
Balance, end of period at Dec. 31, 2016	$ 1,281,814	$ 1,281,814	$ 1,055,934	$ 322,854	$ (96,974)	$ 0
Balance, end of period (in shares) at Dec. 31, 2016			120,630,000

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income (loss), including noncontrolling interests	$ (81,445)	$ (376,980)	$ 195,550
Adjustments to reconcile net income (loss), including noncontrolling interests, to net cash provided by operating activities:
Depreciation and amortization	114,187	120,401	109,345
Non-cash impairment charges	45,107	361,409	0
Amortization of debt discount	5,905	5,957	5,596
Amortization of debt issuance costs	7,733	5,664	4,870
Share-based compensation	5,862	6,543	3,133
Excess tax benefit from share-based compensation	0	0	(68)
Deferred income taxes	14,849	(103,022)	23,154
Equity in losses of investments	2,166	124,345	0
Gain on disposition of assets, net	(1,290)	(92)	(10,240)
Loss on repurchase of long-term debt	3,540	0	0
Unrealized losses and ineffectiveness on derivative contracts, net	(8,800)	18,281	1,320
Changes in operating assets and liabilities:
Accounts receivable, net	(22,437)	36,354	43,963
Other current assets	(2,386)	7,956	(6,461)
Income tax payable	(4,571)	(7,464)	9,088
Accounts payable and accrued liabilities	(630)	(63,817)	12,841
Oil and gas asset retirement costs	0	0	(1,024)
Other non-current, net	(39,076)	(24,730)	(31,582)
Net cash provided by operating activities	38,714	110,805	359,485
Cash flows from investing activities:
Capital expenditures	(186,487)	(320,311)	(336,912)
Distributions from equity investments, net of earnings	1,200	7,000	7,911
Proceeds from sale of equity investment	25,000	0	0
Proceeds from sale of assets	13,177	17,592	13,574
Acquisition of noncontrolling interests	0	0	(20,085)
Net cash used in investing activities	(147,110)	(295,719)	(335,512)
Cash flows from financing activities:
Issuance of Convertible Senior Notes due 2022	125,000	0	0
Repurchase of Convertible Senior Notes due 2032	(138,401)	0	0
Proceeds from Nordea Q5000 Loan	0	250,000	0
Repayment of Nordea Q5000 Loan	(35,714)	(17,857)	0
Repayment of Term Loan	(62,742)	(22,500)	(15,000)
Repayment of MARAD Debt	(5,926)	(5,644)	(5,376)
Debt issuance costs	(4,655)	(1,737)	(3,586)
Distributions to noncontrolling interests	0	0	(1,018)
Net proceeds from issuance of common stock	96,547	0	0
Repurchases of common stock	(341)	(1,121)	(8,382)
Excess tax benefit from share-based compensation	0	0	68
Proceeds from issuance of ESPP shares	708	3,484	3,223
Net cash provided by (used in) financing activities	(25,524)	204,625	(30,071)
Effect of exchange rate changes on cash and cash equivalents	(3,625)	(2,011)	4,390
Net increase (decrease) in cash and cash equivalents	(137,545)	17,700	(1,708)
Cash and cash equivalents:
Balance, beginning of year	494,192	476,492	478,200
Balance, end of year	$ 356,647	$ 494,192	$ 476,492

Organization	12 Months Ended
Organization	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Unless the context indicates otherwise, the terms “we,” “us” and “our” in this Annual Report refer collectively to Helix Energy Solutions Group, Inc. and its subsidiaries (“Helix” or the “Company”). We are an international offshore energy services company that provides specialty services to the offshore energy industry, with a focus on well intervention and robotics operations. We provide services primarily in deepwater in the U.S. Gulf of Mexico, North Sea, Asia Pacific and West Africa regions, and are expanding our operations offshore Brazil. Our Operations We seek to provide services and methodologies that we believe are critical to maximizing production economics. Our “life of field” services are segregated into three reportable business segments: Well Intervention, Robotics and Production Facilities (Note 13). Our Well Intervention segment includes our vessels and equipment used to perform well intervention services primarily in the U.S. Gulf of Mexico, North Sea and Brazil. Our Well Intervention segment also includes intervention riser systems (“IRSs”), some of which we rent out on a stand-alone basis, and subsea intervention lubricators (“SILs”). Our well intervention vessels include the Q4000, the Q5000, the Seawell, the Well Enhancer, and the chartered Skandi Constructor, Siem Helix 1 and Siem Helix 2 vessels. The Q5000 vessel went on contracted rates in May 2016 under our five-year contract with BP. We currently have another semi-submersible well intervention vessel under construction, the Q7000. The two chartered newbuild monohull vessels, the Siem Helix 1 and the Siem Helix 2, are to be used in connection with our contracts to provide well intervention services offshore Brazil. We previously also owned the Helix 534, which we sold in December 2016 (Note 4). Our Robotics segment includes remotely operated vehicles (“ROVs”), trenchers and ROVDrills designed to complement offshore construction and well intervention services, and currently operates three chartered ROV support vessels following the expiration of the Rem Installer charter in July 2016. Another chartered ROV support vessel, the Grand Canyon III, is expected to be in service for us in May 2017. Our Production Facilities segment includes the Helix Producer I (the “HP I”), a ship-shaped dynamic positioning floating production vessel, and the Helix Fast Response System (the “HFRS”), which provides certain operators access to our Q4000 and HP I vessels in the event of a well control incident in the Gulf of Mexico. The HP I was previously contracted to process production from the Phoenix field for the field operator until at least December 31, 2017, and in July 2016 we entered into a new fixed fee agreement for the HP I with the same operator, effective June 1, 2016, for service to the Phoenix field until at least June 1, 2023. The HFRS is currently under contract through March 31, 2018. The Production Facilities segment also includes our ownership interest in Independence Hub, LLC (“Independence Hub”) and previously included our former ownership interest in Deepwater Gateway, L.L.C. (“Deepwater Gateway”) that we sold for $25 million in February 2016 (Note 5).

Summary Of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Summary Of Significant Accounting Policies

Summary of Significant Accounting Policies

Principles of Consolidation

Our consolidated financial statements include the accounts of majority owned subsidiaries. The equity method is used to account for investments in affiliates in which we do not have majority ownership, but have the ability to exert significant influence. We account for our former ownership interest in Deepwater Gateway and our ownership interest in Independence Hub under the equity method of accounting. Noncontrolling interests represent the minority shareholders’ proportionate share of the equity in Kommandor LLC, a Delaware limited liability company formed for the purpose of converting a ferry vessel into the HP I. In February 2014, we acquired our former minority partner’s noncontrolling interests (approximately 19%) in Kommandor LLC for $20.1 million. The consolidated results of Kommandor LLC are included in our Production Facilities segment. All material intercompany accounts and transactions have been eliminated.

Basis of Presentation

Our consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”). Certain reclassifications were made to previously reported amounts in the consolidated financial statements and notes thereto to make them consistent with the current presentation format. We have made all adjustments (which were normal recurring adjustments) that we believe are necessary for a fair presentation of our consolidated financial statements, as applicable.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates.

Cash and Cash Equivalents

Cash and cash equivalents are highly liquid financial instruments with original maturities of three months or less. They are carried at cost plus accrued interest, which approximates fair value.

Accounts and Notes Receivable and Allowance for Uncollectible Accounts

Accounts and notes receivable are stated at the historical carrying amount net of write-offs and allowance for uncollectible accounts. The amount of our net accounts receivable and our note receivable approximates fair value. We establish an allowance for uncollectible accounts based on historical experience as well as any specific collection issues that we have identified. Uncollectible receivables are written off when a settlement is reached for an amount that is less than the outstanding historical balance or when we have determined that the balance will definitively not be collected (Note 16).

Property and Equipment

Property and equipment is recorded at historical cost. Property and equipment is depreciated on a straight line basis over the estimated useful life of each asset. The cost of improvements is capitalized while the cost of repairs and maintenance is charged to expense as incurred. For the years ended December 31, 2016, 2015 and 2014, repair and maintenance expense totaled $25.5 million, $32.8 million and $44.6 million, respectively.

Assets used in operations are assessed for impairment whenever changes in facts and circumstances indicate that the carrying amount of an asset or asset group may not be recoverable because such carrying amount may exceed the asset’s or asset group’s fair value. If, upon review, the sum of undiscounted future cash flows expected to be generated by the asset or asset group is less than its carrying amount, an impairment is recorded. The amount of the impairment recorded is calculated as the difference between the carrying amount of the asset or asset group and its estimated fair value. Individual assets are grouped for impairment purposes at the lowest level where there are identifiable cash flows that are largely independent of the cash flows of other groups of assets. The expected future cash flows used for impairment reviews and related fair value calculations are based on assessments of operating costs, project margins and capital project decisions, considering all available information at the date of review. The fair value of impaired assets is typically determined based on the present values of expected future cash flows using discount rates believed to be consistent with those used by principal market participants or based on a multiple of operating cash flows validated with historical market transactions of similar assets where possible. These fair value measurements fall within Level 3 of the fair value hierarchy.

Assets are classified as held for sale when a formal plan to dispose of the assets exists and those assets meet the held for sale criteria. Assets held for sale are reviewed for potential loss on sale when we commit to a plan to sell and thereafter while those assets are held for sale. Losses are measured as the difference between an asset’s fair value less costs to sell and the asset’s carrying amount. Estimates of anticipated sales prices are judgmental and subject to revision in future periods, although initial estimates are typically based on sales prices for similar assets and other valuation data.

Capitalized Interest

Interest from external borrowings is capitalized on major projects until the assets are ready for their intended use. Capitalized interest is added to the cost of the underlying asset and is amortized over the useful life of the asset in the same manner as the underlying asset. Capitalized interest is a component of our net interest expense (Note 7).

Equity Investments

We periodically review our equity investments for impairment. Under the equity method of accounting, an impairment loss would be recorded whenever the fair value of an equity investment is determined to be below its carrying amount and the reduction is considered to be other than temporary. In judging “other than temporary,” we consider the length of time and extent to which the fair value of the investment has been less than the carrying amount of the equity investment, the near-term and long-term operating and financial prospects of the entity and our longer-term intent of retaining our investment in the entity.

In the event we incur losses in excess of the carrying amount of an equity investment and reduce our investment balance to zero, we would not record additional losses unless (i) we guaranteed obligations of the investee, (ii) we are otherwise committed to provide further financial support for the investee, or (iii) it is anticipated that the investee’s return to profitability is imminent. If we provided a commitment to fund losses, we would continue to record losses resulting in a negative equity method investment, which is presented as a liability.

Goodwill

We are required to perform an annual impairment analysis of goodwill. We elected November 1 to be our annual impairment assessment date for goodwill. However, we could be required to evaluate the recoverability of goodwill prior to the annual assessment date if we experience disruption to the business, unexpected significant declines in operating results, divestiture of a significant component of the business, emergence of unanticipated competition, loss of key personnel or a sustained decline in market capitalization. At the time of our annual assessment of goodwill on November 1, 2016, we had one reporting unit with goodwill.

We first assess qualitative factors in order to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, including goodwill. Some of the qualitative factors evaluated include, among other things, the results of the most recent impairment analysis, the most recent operating results of the reporting unit, the current outlook for the reporting unit, and the current conditions of the market in which the reporting unit operates. If the qualitative assessment indicates a potential impairment, we perform the first step of the goodwill impairment analysis as described below. Our policy is to bypass the qualitative assessment at least once every three years and perform the first step of the goodwill impairment analysis. We elected to perform the first step of the goodwill impairment analysis for both 2015 and 2016 in light of the continuation of industry-wide downturn as a result of the substantial decline in oil prices since late 2014.

The goodwill impairment analysis is a two-step process. The first step is to identify whether a potential impairment exists by comparing the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not considered to have a potential impairment and the second step of the impairment analysis is not necessary. However, if the carrying amount of a reporting unit exceeds its fair value, the second step is performed to determine if goodwill is impaired and to measure the amount of impairment loss to recognize, if any.

The second step compares the implied fair value of goodwill with the carrying amount of goodwill. If the implied fair value of goodwill exceeds the carrying amount, then goodwill is not considered impaired. However, if the carrying amount of goodwill exceeds the implied fair value, an impairment loss is recognized in an amount equal to that excess. The implied fair value of goodwill is determined in the same manner as the amount of goodwill recognized in a business combination (i.e., the fair value of the reporting unit is allocated to all the assets and liabilities, including any unrecognized intangible assets, as if the reporting unit were acquired in a business combination).

We use both the income approach and the market approach to estimate the fair value of our reporting units under the first step of our goodwill impairment analysis. Under the income approach, a discounted cash flow analysis is performed requiring us to make various judgmental assumptions about future revenue, operating margins, growth rates and discount rates. These judgmental assumptions are based on our budgets, long-term business plans, economic projections, anticipated future cash flows and market place data. Under the market approach, the fair value of each reporting unit is calculated by applying an average peer total invested capital EBITDA (defined as earnings before interest, income taxes and depreciation and amortization) multiple to future forecasted EBITDA for each reporting unit. Judgment is required when selecting peer companies that operate in the same or similar lines of business and are potentially subject to the same economic risks. We also perform a market capitalization reconciliation by comparing the fair value of equity (fair value of total invested capital less fair value of total debt) to market capitalization and evaluate the reasonableness of the implied equity premium.

Our goodwill subject to impairment analysis in 2016 was associated with our Robotics segment. As a result of our 2016 goodwill impairment analysis, we recorded an impairment charge of $45.1 million to write off the goodwill associated with our robotics reporting unit. Our goodwill subject to impairment analysis in 2015 and 2014 was associated with our Well Intervention and Robotics segments. As a result of our 2015 goodwill impairment analysis, we recorded an impairment charge of $16.4 million to write off the goodwill associated with our U.K. well intervention reporting unit. As of November 1, 2015, the fair value of our robotics reporting unit exceeded the carrying amount of goodwill based on the first step of the impairment analysis and no impairment was recorded. In 2014, we performed the qualitative assessment as described above and concluded that there was no indication of goodwill impairment. We did not record any amount of goodwill impairment in 2014.

Recertification Costs and Deferred Dry Dock Costs

Our vessels are required by regulation to be periodically recertified. Recertification costs are incurred while a vessel is in dry dock. In addition, routine repairs and maintenance are performed and at times, major replacements and improvements are performed. We expense routine repairs and maintenance costs as they are incurred. We defer and amortize dry dock and related recertification costs over the length of time for which we expect to receive benefits from the dry dock and related recertification, which is generally 30 months but can be as long as 60 months if the appropriate permitting is obtained. A dry dock and related recertification process typically lasts one to two months, a period during which the vessel is idle and generally not available to earn revenue. Major replacements and improvements that extend the vessel’s economic useful life or functional operating capability are capitalized and depreciated over the vessel’s remaining economic useful life.

As of December 31, 2016 and 2015, capitalized deferred dry dock costs included within “Other assets, net” in the accompanying consolidated balance sheets (Note 3) totaled $14.8 million and $19.6 million (net of accumulated amortization of $10.7 million and $18.3 million), respectively. During the years ended December 31, 2016, 2015 and 2014, dry dock amortization expense was $14.0 million, $10.8 million and $14.1 million, respectively.

Revenue Recognition

Revenues from our services are derived from contracts, which are both short-term and long-term in duration. Our long-term services contracts are contracts that contain either lump-sum provisions or provisions for specific time, material and equipment charges, which are billed in accordance with the terms of such contracts. We recognize revenue as it is earned at estimated collectible amounts. Further, we record revenues net of taxes collected from customers and remitted to governmental authorities.

Unbilled revenue represents revenue attributable to work completed prior to period end that has not yet been invoiced. All amounts included in unbilled revenue are expected to be billed and collected within one year. However, we also monitor the collectability of our outstanding trade receivables on a continual basis in connection with our evaluation of allowance for doubtful accounts.

Dayrate Contracts. Revenues generated from specific time, material and equipment contracts are generally earned on a dayrate basis and recognized as amounts are earned in accordance with contract terms. Certain dayrate contracts with built-in rate changes require us to record revenues on a straight-line basis. We may receive revenues for mobilization of equipment and personnel under dayrate contracts. Revenues related to mobilization are deferred and recognized over the period in which contracted services are performed using the straight-line method. Incremental costs incurred directly for mobilization of equipment and personnel to the contracted site, which typically consist of materials, supplies and transit costs, also are deferred and recognized using the same straight line method. Our policy to amortize the revenues and costs related to mobilization on a straight-line basis over the estimated contract service period is consistent with the general pace of activity, level of services being provided and dayrates being earned over the contract period. Mobilization costs to move vessels when a contract does not exist are expensed as incurred.

Lump Sum Contracts. Revenue on significant lump sum contracts is recognized under the percentage-of-completion method based on the ratio of costs incurred to total estimated costs at completion. In determining whether a contract should be accounted for using the percentage-of-completion method, we consider whether:


•	the customer provides specifications for the provision of services;


•	we can reasonably estimate our progress towards completion and our costs;


•	the contract includes provisions for enforceable rights regarding the goods or services to be provided, consideration to be received, and the manner and terms of payment;


•	the customer can be expected to satisfy its obligations under the contract; and


•	we can be expected to perform our contractual obligations.

Under the percentage-of-completion method, we recognize estimated contract revenue based on costs incurred to date as a percentage of total estimated costs. Changes in the expected cost of materials and labor, productivity, scheduling and other factors affect the total estimated costs. Additionally, weather and other external factors outside of our control may affect the progress and estimated cost of a project’s completion, and therefore the timing of revenue recognition. We routinely review estimates related to our contracts and reflect revisions to profitability in earnings on a current basis. If a current estimate of total contract cost indicates an ultimate loss on a contract, we recognize the projected loss in full when it is first determined. We recognize additional contract revenue related to claims when the claim is probable and legally enforceable.

Revenue from Royalty Interests

Revenues from royalty interests are recognized according to monthly oil and gas production on an entitlement basis. Revenues for royalty interests are reflected in “Other income - oil and gas” in the accompanying consolidated statements of operations.

Income Taxes

Deferred income taxes are based on the differences between financial reporting and tax bases of assets and liabilities. We utilize the liability method of computing deferred income taxes. The liability method is based on the amount of current and future taxes payable using tax rates and laws in effect at the balance sheet date. Income taxes have been provided based upon the tax laws and rates in the countries in which operations are conducted and income is earned. A valuation allowance for deferred tax assets is recorded when it is more likely than not that some or all of the benefit from the deferred tax asset will not be realized. We consider the undistributed earnings of our non-U.S. subsidiaries without operations in the U.S. to be permanently reinvested.

It is our policy to provide for uncertain tax positions and the related interest and penalties based upon management’s assessment of whether a tax benefit is more likely than not to be sustained upon examination by tax authorities. At December 31, 2016, we believe that we have appropriately accounted for any unrecognized tax benefits. To the extent we prevail in matters for which a liability for an unrecognized tax benefit is established or are required to pay amounts in excess of the liability, our effective tax rate in a given financial statement period may be affected.

Share-Based Compensation

Share-based compensation is measured at the grant date based on the estimated fair value of an award. Share-based compensation based solely on service conditions is recognized on a straight-line basis over the vesting period of the related shares. Tax deduction benefits for a share-based award in excess of recognized compensation cost is reported as a financing cash flow rather than as an operating cash flow.

Compensation cost for restricted stock is the product of grant date fair value of each share and the number of shares granted and is recognized over the respective vesting periods on a straight-line basis.

The estimated fair value of performance share units (“PSUs”) is determined using a Monte Carlo simulation model. Compensation cost for PSUs that are accounted for as equity awards is measured based on the estimated grant date fair value and recognized over the vesting period on a straight-line basis. PSUs that are accounted for as liability awards are measured based on the estimated fair value at the balance sheet date and changes in fair value of the awards are recognized in earnings. Cumulative compensation cost for vested liability PSU awards equals the actual cash payout amount upon vesting. To the extent the recognized fair value of the modified liability awards is less than the compensation cost associated with the grant date fair value of the original equity awards at the end of a reporting period, the higher amount is recorded as share-based compensation. The amount of cumulative compensation cost recognized in excess of the fair value of the modified liability awards is recorded in equity.

Foreign Currency

Because we operate in various regions around the world, we conduct a portion of our business in currencies other than the U.S. dollar. Results of operations for our non-U.S. subsidiaries are translated into U.S. dollars using average exchange rates during the period. Assets and liabilities of these foreign subsidiaries are translated into U.S. dollars using the exchange rate in effect at December 31, 2016 and 2015 and the resulting translation adjustments, which were unrealized losses of $35.9 million and $12.8 million, respectively, are included in “Accumulated other comprehensive loss” (“Accumulated OCI”), a component of shareholders’ equity.

For the years ended December 31, 2016, 2015 and 2014, our foreign currency transaction gains (losses) totaled $0.2 million, $(1.2) million and $2.5 million, respectively. These realized amounts are exclusive of any gains or losses from our foreign currency exchange derivative contracts. All foreign currency transaction gains and losses are recognized currently in the consolidated statements of operations.

Derivative Instruments and Hedging Activities

Our business is exposed to market risks associated with interest rates and foreign currency exchange rates. Our risk management activities involve the use of derivative financial instruments to hedge the impact of market risk exposure related to variable interest rates and foreign currency exchange rates. To reduce the impact of these risks on earnings and increase the predictability of our cash flows, from time to time we enter into certain derivative contracts, including interest rate swaps and foreign currency exchange contracts. All derivative instruments are reflected in the accompanying consolidated balance sheets at fair value.

We formally document all relationships between hedging instruments and the related hedged items, as well as our risk management objectives, strategies for undertaking various hedge transactions and our methods for assessing and testing correlation and hedge ineffectiveness. All hedging instruments are linked to the hedged asset, liability, firm commitment or forecasted transaction. We also assess, both at the inception of the hedge and on an on-going basis, whether the derivative instruments that are designated as hedging instruments are highly effective in offsetting changes in cash flows of the hedged items. We discontinue hedge accounting if we determine that a derivative is no longer highly effective as a hedge, or it is probable that a hedged transaction will not occur. If hedge accounting is discontinued because it is probable the hedged transaction will not occur, deferred gains or losses on the hedging instruments are recognized in earnings immediately. If the forecasted transaction continues to be probable of occurring, any deferred gains or losses in Accumulated OCI are amortized to earnings over the remaining period of the original forecasted transaction.

We engage solely in cash flow hedges. Hedges of cash flow exposure are entered into to hedge a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability. The fair value of our interest rate swaps is calculated as the discounted cash flows of the difference between the rate fixed by the hedging instrument and the LIBOR forward curve over the remaining term of the hedging instrument. The fair value of our foreign currency exchange contracts is calculated as the discounted cash flows of the difference between the fixed payment specified by the hedging instrument and the expected cash inflow of the forecasted transaction using a foreign currency forward curve. Changes in the fair value of derivative instruments that are designated as cash flow hedges are deferred to the extent that the hedges are effective. These fair value changes are recorded as a component of Accumulated OCI until the hedged transactions occur and are recognized in earnings. The ineffective portion of changes in the fair value of cash flow hedges is recognized immediately in earnings. In addition, any change in the fair value of a derivative instrument that does not qualify for hedge accounting is recorded in earnings in the period in which the change occurs.

Interest Rate Risk

From time to time, we enter into interest rate swaps to stabilize cash flows related to our long-term variable interest rate debt. Changes in the fair value of interest rate swaps are deferred to the extent the swaps are effective. These changes are recorded as a component of Accumulated OCI until the anticipated interest is recognized as interest expense. The ineffective portion of the interest rate swaps, if any, is recognized immediately in earnings within the line titled “Net interest expense.”

Foreign Currency Exchange Rate Risk

Because we operate in various regions around the world, we conduct a portion of our business in currencies other than the U.S. dollar. We enter into foreign currency exchange contracts from time to time to stabilize expected cash outflows related to our vessel charters that are denominated in foreign currencies. Changes in the fair value of foreign currency exchange contracts are deferred to the extent the contracts are effective. These changes are recorded as a component of Accumulated OCI until the forecasted vessel charter payments are made and recorded as cost of sales. The ineffective portion of these foreign currency exchange contracts, if any, and changes in the fair value of foreign currency exchange contracts that do not qualify as cash flow hedges are recognized immediately in earnings within the line titled “Other income (expense), net.”

Earnings Per Share

The presentation of basic earnings per share (“EPS”) amounts on the face of the accompanying consolidated statements of operations is computed by dividing the net income applicable to our common shareholders by the weighted average shares of our outstanding common stock. The calculation of diluted EPS is similar to basic EPS, except that the denominator includes dilutive common stock equivalents and the income included in the numerator excludes the effects of the impact of dilutive common stock equivalents, if any. We have shares of restricted stock issued and outstanding that are currently unvested. Holders of such shares of unvested restricted stock are entitled to the same liquidation and dividend rights as the holders of our outstanding unrestricted common stock and the shares of restricted stock are thus considered participating securities. Under applicable accounting guidance, the undistributed earnings for each period are allocated based on the participation rights of both the common shareholders and holders of any participating securities as if earnings for the respective periods had been distributed. Because both the liquidation and dividend rights are identical, the undistributed earnings are allocated on a proportionate basis. Further, we are required to compute EPS amounts under the two class method in periods in which we have earnings. For periods in which we have a net loss we do not use the two class method as holders of our restricted shares are not contractually obligated to share in such losses.

Major Customers and Concentration of Credit Risk

The market for our products and services is primarily the offshore oil and gas and renewable industries. Oil and gas companies spend capital on exploration, drilling and production operations, the amount of which is generally dependent on the prevailing view of future oil and gas prices which are subject to many external factors that may contribute to significant volatility. Our customers consist primarily of major and independent oil and gas producers and suppliers, pipeline transmission companies, alternative (renewable) energy companies and offshore engineering and construction firms. We perform ongoing credit evaluations of our customers and provide allowances for probable credit losses when necessary. The percent of consolidated revenue from major customers (those representing 10% or more of our consolidated revenues) is as follows: 2016 — BP (17%) and Shell (11%), 2015 — Shell (16%) and Talos (11%), and 2014 — Anadarko (13%). Most of the concentration of revenues was generated by our Well Intervention business.

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value accounting rules establish a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:


•	Level 1. Observable inputs such as quoted prices in active markets;


•	Level 2. Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and


•	Level 3. Unobservable inputs for which there is little or no market data, which require the reporting entity to develop its own assumptions.

Assets and liabilities measured at fair value are based on one or more of three valuation approaches as described in Note 17.

Asset Retirement Obligations

We retained the reclamation obligations associated with one oil and gas property located in the U.S. Gulf of Mexico, which we sold in February 2013. For the year ended December 31, 2014, we recorded a $7.2 million insurance reimbursement related to asset retirement work previously performed on this property.

New Accounting Standards

In May 2014, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” This ASU provides a single five-step approach to account for revenue arising from contracts with customers. The ASU requires an entity to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This revenue standard was originally effective prospectively for annual reporting periods beginning after December 15, 2016, including interim periods. In August 2015, the FASB issued ASU No. 2015-14 to defer the effective date of ASU No. 2014-09 by one year to annual reporting periods beginning after December 15, 2017. Adoption as of the original effective date is permitted. In March 2016, the FASB issued ASU No. 2016-08, which amends the guidance to clarify the implementation issues on principal versus agent considerations (gross versus net revenue presentation). In April 2016, the FASB issued ASU No. 2016-10, which amends the guidance with respect to certain implementation issues on identifying performance obligations and accounting for licenses of intellectual property. In May 2016, the FASB issued ASU No. 2016-12, which provides certain narrow-scope improvements and practical expedients to the guidance. In December 2016, the FASB issued ASU No. 2016-20, which provides certain technical corrections and improvements to the guidance. The new revenue standard permits companies to either apply the requirements retrospectively to all prior periods presented or apply the requirements in the year of adoption through a cumulative adjustment. We are in the process of assessing differences between the new revenue standard and current accounting practices (gap analysis). Remaining implementation matters include completing the gap analysis, establishing new policies, procedures and controls, and quantifying any adjustments upon adoption. We have not yet determined if we will apply the full retrospective or the modified retrospective method.

In April 2015, the FASB issued ASU No. 2015-03, “Simplifying the Presentation of Debt Issuance Costs.” This ASU requires that debt issuance costs related to a recognized debt liability be reported on the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. In August 2015, the FASB issued ASU No. 2015-15, “Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements.” This ASU includes an SEC staff announcement that the SEC staff will not object to an entity presenting the cost of securing a revolving line of credit as an asset, regardless of whether a balance is outstanding. The subject of this ASU was not previously addressed by ASU No. 2015-03. We adopted this guidance retrospectively in the first quarter of 2016. As a result, we presented $12.0 million of unamortized debt issuance costs that had been included in “Other assets, net” in our consolidated balance sheet as of December 31, 2015 as direct deductions from the carrying amounts of the related debt liabilities.

In November 2015, the FASB issued ASU No. 2015-17, “Balance Sheet Classification of Deferred Taxes.” This ASU requires companies to classify all deferred tax assets and liabilities as non-current on the balance sheet instead of separating deferred taxes into current and non-current amounts. The current requirement that deferred tax liabilities and assets of a tax-paying component of an entity be offset and presented as a single amount is not affected by this guidance. The guidance is effective prospectively for annual reporting periods beginning after December 15, 2016, including interim periods. We do not expect this ASU to materially affect our consolidated financial statements except for certain reclassifications between current deferred tax assets and non-current deferred tax liabilities.

In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842).” This ASU amends the existing accounting standards for leases. The amendments are intended to increase transparency and comparability among organizations by requiring recognition of lease assets and lease liabilities on the balance sheet and disclosure of key information about leasing arrangements. The guidance is effective for annual reporting periods beginning after December 15, 2018, including interim periods. Early adoption is permitted. The guidance is required to be adopted at the earliest period presented using a modified retrospective approach. We are currently evaluating the impact these amendments will have on our consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, “Improvements to Employee Share-Based Payment Accounting.” This ASU simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, forfeitures, classification of awards as either equity or liabilities, and classification in the statement of cash flows. The guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods. We do not expect this ASU to materially affect our consolidated financial statements with the exception of recognizing excess tax benefits or tax deficiencies on our statements of operations in future periods.

In June 2016, the FASB issued ASU No. 2016-13, “Measurement of Credit Losses on Financial Instruments.” This ASU replaces the current incurred loss model for measurement of credit losses on financial assets including trade receivables with a forward-looking expected loss model based on historical experience, current conditions and reasonable and supportable forecasts. The guidance is effective for annual reporting periods beginning after December 15, 2019, including interim periods. We are currently evaluating the impact this guidance will have on our consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, “Classification of Certain Cash Receipts and Cash Payments.” This ASU addresses how certain cash receipts and cash payments are presented and classified in the statement of cash flows with the objective of reducing the existing diversity in practice. The guidance is effective for annual reporting periods beginning after December 15, 2017, including interim periods. Early adoption is permitted. An entity that elects early adoption of the amendment under this ASU must adopt all aspects of the amendment in the same period. We do not expect this ASU to have a material impact on our statements of cash flows.

In October 2016, the FASB issued ASU No. 2016-16, “Intra-Entity Transfers of Assets Other Than Inventory.” This ASU eliminates the exception in current guidance that prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party. Under the new ASU, an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The guidance is effective for annual reporting periods beginning after December 15, 2017, including interim periods. Early adoption is permitted. We are currently evaluating the impact this guidance will have on our consolidated financial statements.

We do not expect any other recent accounting standards to have a material impact on our financial position, results of operations or cash flows.

Details Of Certain Accounts

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Details Of Certain Accounts

Details of Certain Accounts

Other current assets consist of the following (in thousands):



	December 31,
	2016		2015

Note receivable (Note 4)	$	10,000	$	10,000
Prepaid insurance	4,426		5,433
Other prepaids	9,547		10,142
Deferred costs	7,971		609
Spare parts inventory	2,548		4,985
Income tax receivable	880		—
Value added tax receivable	1,345		7,842
Other	671		507
Total other current assets	$	37,388	$	39,518

Other assets, net consist of the following (in thousands):



	December 31,
	2016		2015

Note receivable, net ⁽¹⁾	$	2,827	$	—
Prepaids	6,418		—
Deferred dry dock costs, net (Note 2)	14,766		19,615
Deferred costs ⁽²⁾	30,738		—
Deferred financing costs, net ⁽³⁾	3,745		7,863
Charter fee deposit (Note 14)	12,544		12,544
Other	1,511		1,586
Total other assets, net	$	72,549	$	41,608


(1)	Amount, net of allowance of $4.2 million, relates to an agreement we entered into with one of our customers to defer their payment obligations until June 30, 2018. Interest at a rate of 3% per annum is payable semi-annually.


(2)	Amount relates to deferred mobilization costs (Note 2).


(3)	Represents unamortized debt issuance costs related to our Revolving Credit Facility (Note 7).

Accrued liabilities consist of the following (in thousands):



	December 31,
	2016		2015

Accrued payroll and related benefits	$	20,705	$	14,775
Deferred revenue	8,911		12,841
Accrued interest	3,758		4,854
Derivative liability (Note 18)	18,730		23,192
Taxes payable excluding income tax payable	1,214		8,136
Other	5,296		7,843
Total accrued liabilities	$	58,614	$	71,641

Other non-current liabilities consist of the following (in thousands):



	December 31,
	2016		2015

Investee losses in excess of investment (Note 5)	$	10,238	$	8,308
Deferred gain on sale of property (Note 4)	5,761		—
Deferred revenue	8,598		—
Derivative liability (Note 18)	20,191		39,709
Other	8,197		3,398
Total other non-current liabilities	$	52,985	$	51,415

Property And Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property And Equipment

Property and Equipment

The following is a summary of the gross components of property and equipment (dollars in thousands):



		December 31,
	Estimated Useful Life	2016		2015

Vessels	15 to 30 years	$	1,860,379	$	1,944,753
ROVs, trenchers and ROVDrills	10 years	309,603		311,971
Machinery, equipment, buildings and leasehold improvements	5 to 30 years	280,908		288,133
Total property and equipment		$	2,450,890	$	2,544,857

In January 2014, we sold our spoolbase located in Ingleside, Texas for $45 million. In connection with this sale, we received $15 million in cash and a $30 million secured promissory note. Interest on the note is payable quarterly at a rate of 6% per annum. We received $2.5 million, $7.5 million and $10 million of principal payments on this note in December 2014, January 2015 and December 2015, respectively. The remaining $10 million principal balance, which was due on December 31, 2016, has not been paid. A notice of foreclosure of our lien against this property to secure the $30 million promissory note has been filed and we expect to collect the full balance of this note receivable.

Our assessment at December 31, 2015 indicated impairment on the Helix 534 and the HP I. We impaired these assets based on the difference between the carrying amount and the estimated fair value. The fair value of the Helix 534 was based on its estimated salvage value according to current market pricing. We recorded an impairment charge of $205.2 million to reduce the carrying amount of the Helix 534 to its estimated fair value of $1.0 million and to write off deferred dry dock costs of $9.0 million associated with the Helix 534. We estimated the fair value of the HP I based on the present value of its expected future cash flows. We recorded an impairment charge of $133.4 million to reduce the carrying amount of the HP I to its estimated fair value of $124.3 million. In addition, we recorded impairment charges of $6.3 million to write off capitalized costs associated with certain vessel projects that we no longer expected to materialize.

In January 2016, we sold our office and warehouse property located in Aberdeen, Scotland for approximately $11 million and entered into a separate agreement with the same party to lease back the facility for a lease term of 15 years with two five-year options to extend the lease at our option. A gain of approximately $7.6 million from the sale of this property is deferred and amortized over the 15-year minimum lease term.

In December 2016, we sold the Helix 534 vessel to a third party for approximately $2.8 million, including $0.4 million held in escrow until certain contingencies are resolved. We recorded a gain of approximately $1.3 million from the sale of the vessel, net of selling expenses. The $0.4 million contingent gain is deferred and will not be recognized until the payment is released to us from escrow.

Equity Investments

12 Months Ended

Dec. 31, 2016

Equity Method Investments and Joint Ventures [Abstract]

Equity Investments

We have a 20% ownership interest in Independence Hub that we account for using the equity method of accounting. Independence Hub owns the “Independence Hub” platform located in Mississippi Canyon Block 920 in a water depth of 8,000 feet. We previously had a 50% ownership interest in Deepwater Gateway, which owns and operates a tension leg platform production hub primarily for Anadarko Petroleum Corporation’s Marco Polo field in the Deepwater Gulf of Mexico. Our Production Facilities segment includes our investment in Independence Hub that is accounted for under the equity method, and previously included our former ownership interest in Deepwater Gateway.

In July 2015, Enterprise Products Partners L.P. (“Enterprise”) sold its offshore Gulf of Mexico pipelines and services business to Genesis Energy, L.P. (“Genesis”) for approximately $1.5 billion. Enterprise’s ownership interests in both Deepwater Gateway and Independence Hub were included in the sale. In December 2015, we were notified by Genesis that the operator of the facility no longer forecasted utilization of the “Independence Hub” platform and planned to turn over the platform for decommissioning. In December 2015, Independence Hub recorded an impairment charge of $343.3 million to reduce the carrying amount of the platform assets to their estimated fair value of zero. At December 31, 2016 and 2015, Independence Hub’s estimated asset retirement obligations amounted to $52.5 million and $42.1 million, respectively, reflecting the estimated costs to decommission the platform. Since we are committed to providing the necessary level of financial support to enable Independence Hub to pay its obligations as they become due, we recorded liabilities of $10.2 million and $8.3 million at December 31, 2016 and 2015, respectively, for our share of the estimated obligations, net of remaining working capital. These liabilities are reflected in “Other non-current liabilities” in the accompanying consolidated balance sheets. For the year ended December 31, 2016, we recorded losses totaling $2.2 million to account for our share of losses from Independence Hub. For the year ended December 31, 2015, we recorded losses totaling $74.9 million to account for our 20% share of losses from Independence Hub and to write off the remaining capitalized interest of $3.6 million and a $1.0 million participation fee that we paid in 2004. These losses included our share of the impairment charge that Independence Hub recorded in December 2015.

Additionally in December 2015, Deepwater Gateway recorded an impairment charge of $96.7 million to reduce the carrying amount of its long-lived assets to their estimated fair value of $70.8 million. Deepwater Gateway’s estimated asset retirement obligations as of December 31, 2015 amounted to $20.8 million. For the year ended December 31, 2015, we recorded losses totaling $49.4 million to account for our 50% share of losses from Deepwater Gateway and to write off the remaining capitalized interest of $1.2 million. These losses included our share of an impairment charge that Deepwater Gateway recorded in December 2015. Our investment in Deepwater Gateway totaled $26.2 million as of December 31, 2015. In February 2016, we received a cash distribution of $1.2 million and sold our ownership interest in Deepwater Gateway to a subsidiary of Genesis for $25 million.

We received the following distributions from our equity method investments (in thousands):



	Year Ended December 31,
	2016		2015		2014

Deepwater Gateway	$	1,200	$	5,200	$	6,150
Independence Hub	—		1,800		2,640
Total	$	1,200	$	7,000	$	8,790

Equity method investments were immaterial to our 2016 consolidated financial results. The summarized aggregated financial information related to our equity method investments for 2014 and 2015 is as follows (in thousands):



	Year Ended December 31,
	2015			2014

Revenues	$	14,791		$	23,284
Operating income (loss)	(448,138		)	411
Net income (loss)	(448,138		)	411



	December 31,
	2015

Current assets	$	3,181
Non-current assets	70,812
Current liabilities	180
Non-current liabilities	62,951

Goodwill

12 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

The changes in the carrying amount of goodwill are as follows (in thousands):



	Well Intervention			Robotics			Total

Balance at December 31, 2014	$	17,039		$	45,107		$	62,146
Impairment loss	(16,399		)	—			(16,399		)
Other adjustments ⁽¹⁾	(640		)	—			(640		)
Balance at December 31, 2015	—			45,107			45,107
Impairment loss	—			(45,107		)	(45,107		)
Balance at December 31, 2016	$	—		$	—		$	—


(1)	Reflects foreign currency adjustment related to the goodwill of our U.K. well intervention reporting unit.

Long-Term Debt

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Long-Term Debt

Long-term debt consists of the following (in thousands):



	December 31,
	2016			2015

Term Loan (matures June 2018)	$	192,258		$	255,000
2022 Notes (mature May 2022)	125,000			—
2032 Notes (mature March 2032)	60,115			200,000
MARAD Debt (matures February 2027)	83,222			89,148
Nordea Q5000 Loan (matures April 2020)	196,429			232,143
Unamortized debt discounts	(19,094		)	(14,963		)
Unamortized debt issuance costs	(11,963		)	(11,993		)
Total debt	625,967			749,335
Less current maturities	(67,571		)	(71,640		)
Long-term debt	$	558,396		$	677,695

Credit Agreement

In June 2013, we entered into a credit agreement (the “Credit Agreement”) with a group of lenders pursuant to which we borrowed $300 million under a term loan (the “Term Loan”) and, subject to the terms of the Credit Agreement, may borrow additional amounts (the “Revolving Loans”) and/or obtain letters of credit under a revolving credit facility (the “Revolving Credit Facility”) up to $600 million (reduced to $400 million pursuant to the February 2016 amendment to the Credit Agreement, as described below). Pursuant to the Credit Agreement, subject to existing lender participation and/or the participation of new lenders, and subject to standard conditions precedent, we may obtain an increase of up to $200 million in aggregate commitments with respect to the Revolving Credit Facility, additional term loans or a combination thereof. As of December 31, 2016, we had no borrowings under the Revolving Credit Facility and our available borrowing capacity under that facility, based on the leverage ratio covenant, totaled $18.9 million, net of $4.1 million of letters of credit issued.

The Term Loan and the Revolving Loans (together, the “Loans”) bear interest, at our election, in relation to either the base rate established by Bank of America N.A. or to a LIBOR rate, provided that all Swing Line Loans (as defined in the Credit Agreement) will be base rate loans.

The Loans or portions thereof bearing interest at the base rate currently bear interest at a per annum rate equal to the base rate plus a margin ranging from 1.00% to 3.00%. The Loans or portions thereof bearing interest at a LIBOR rate currently bear interest at the LIBOR rate selected by us plus a margin ranging from 2.00% to 4.00%. A letter of credit fee is payable by us equal to our applicable margin for LIBOR rate Loans multiplied by the daily amount available to be drawn under outstanding letters of credit. Margins on the Loans vary in relation to the consolidated interest coverage ratio, as provided by the Credit Agreement. We also pay a fixed commitment fee of 0.50% on the unused portion of our Revolving Credit Facility. The Term Loan currently bears interest at the one-month LIBOR rate plus 4.50%. In September 2013, we entered into various interest rate swap contracts to fix the one-month LIBOR rate on a portion of our borrowings under the Term Loan (Note 18). The total notional amount of the swaps (initially $148.1 million) decreased in proportion to the reduction in the principal amount outstanding under our Term Loan. The fixed LIBOR rates were approximately 75 basis points. The term of these swap contracts, which were settled monthly, expired in October 2016.

The Term Loan is repayable in scheduled principal installments (currently $25.6 million per year), payable quarterly, with a balloon payment of $160.2 million at maturity. These installment amounts are subject to adjustment for any prepayments on the Term Loan. We may elect to prepay amounts outstanding under the Term Loan without premium or penalty, but may not reborrow any amounts prepaid. We elected to prepay $8 million in September 2016 and $25 million in December 2016. We may also prepay amounts outstanding under the Revolving Loans without premium or penalty, and may reborrow any amounts paid up to the amount of the Revolving Credit Facility. The Loans mature on June 19, 2018.

The Credit Agreement and the other documents entered into in connection with the Credit Agreement (together, the “Loan Documents”) include terms and conditions, including covenants and prepayment requirements, that we consider customary for this type of transaction. The covenants include restrictions on our and our subsidiaries’ ability to grant liens, incur indebtedness, make investments, merge or consolidate, sell or transfer assets, pay dividends and incur capital expenditures. In addition, the Credit Agreement obligates us to meet certain financial ratios, including the Consolidated Interest Coverage Ratio and the Consolidated Leverage Ratio (as defined in the Credit Agreement).

In January 2016, we amended the Credit Agreement to permit the sale and lease back of certain office and warehouse property located in Aberdeen, Scotland. In February 2016, we amended the Credit Agreement to decrease the lenders’ commitment under the Revolving Credit Facility from $600 million to $400 million, and as a result, we recorded a $2.5 million interest charge to accelerate the amortization of debt issuance costs in proportion to the reduced commitment.

Also pursuant to the February 2016 amendment to the Credit Agreement,


(a)	The minimum permitted Consolidated Interest Coverage Ratio was revised as follows:



Four Fiscal Quarters Ending	Minimum Consolidated Interest Coverage Ratio

December 31, 2016 through and including March 31, 2017	2.75	to 1.00
June 30, 2017 and each fiscal quarter thereafter	3.00	to 1.00


(b)	The maximum permitted Consolidated Leverage Ratio was revised as follows:



Four Fiscal Quarters Ending	Maximum Consolidated Leverage Ratio

December 31, 2016	5.00	to 1.00
March 31, 2017	4.75	to 1.00
June 30, 2017	4.25	to 1.00
September 30, 2017	3.75	to 1.00
December 31, 2017 and each fiscal quarter thereafter	3.50	to 1.00

(c)

A financial covenant was established requiring us to maintain a minimum cash balance if our Consolidated Leverage Ratio is 3.50x or greater, as described below. This minimum cash balance is not required to be maintained in any particular bank account or to be segregated from other cash balances in bank accounts that we use in our ordinary course of business. Because the use of this cash is not legally restricted notwithstanding this maintenance covenant, we present it as cash and cash equivalents on our balance sheet. As of December 31, 2016, we needed to maintain an aggregate cash balance of at least $150 million in order to comply with this covenant.



Consolidated Leverage Ratio	Minimum Cash Balance

Greater than or equal to 4.50x	$150,000,000.00
Greater than or equal to 4.00x but less than 4.50x	100,000,000.00
Greater than or equal to 3.50x but less than 4.00x	50,000,000.00
Less than 3.50x	0.00

We have designated five of our foreign subsidiaries, and may designate any newly established foreign subsidiaries, as subsidiaries that are not generally subject to the Credit Agreement’ covenants (the “Unrestricted Subsidiaries”), provided we meet certain liquidity requirements, in which case EBITDA (net of cash distributions to the parent) of the Unrestricted Subsidiaries is not included in the calculations with respect to our financial covenants. Our obligations under the Credit Agreement are guaranteed by our wholly owned domestic subsidiaries (except Cal Dive I – Title XI, Inc.) and Canyon Offshore Limited, a wholly owned Scottish subsidiary. Our obligations under the Credit Agreement, and of the guarantors under their guaranty, are secured by most of our assets of the parent and our wholly owned domestic subsidiaries (except Cal Dive I – Title XI, Inc.) and Canyon Offshore Limited, plus pledges of up to two-thirds of the shares of certain foreign subsidiaries.

Convertible Senior Notes Due 2022

On November 1, 2016, we completed a public offering and sale of our Convertible Senior Notes due 2022 (the “2022 Notes”) in the aggregate principal amount of $125 million. The net proceeds from the issuance of the 2022 Notes were $121.7 million, after deducting the underwriter’s discounts and commissions and offering expenses. We used net proceeds from the issuance of the 2022 Notes, as well as cash on hand, to repurchase and retire $125 million of aggregate principal amount of the 2032 Notes (see “Convertible Senior Notes Due 2032” below), in separate, privately negotiated transactions.

The 2022 Notes bear interest at a rate of 4.25% per annum, and are payable semi-annually in arrears on November 1 and May 1 of each year, beginning on May 1, 2017. The 2022 Notes mature on May 1, 2022, unless earlier converted, redeemed or repurchased. During certain periods and subject to certain conditions (as described in the Indenture governing the 2022 Notes) the 2022 Notes are convertible by the holders into shares of our common stock at an initial conversion rate of 71.9748 shares of common stock per $1,000 principal amount (which represents an initial conversion price of approximately $13.89 per share of common stock), subject to adjustment in certain circumstances as set forth in the Indenture governing the 2022 Notes. We have the right and the intention to settle any such future conversions in cash.

Prior to November 1, 2019, the 2022 Notes are not redeemable. On or after November 1, 2019, holders of the 2022 Notes may require us to repurchase the notes following a “fundamental change,” as defined in the 2022 Notes documentation. On or after November 1, 2019, we may redeem all or any portion of the 2022 Notes, at our option, subject to certain conditions, at a redemption price payable in cash equal to 100% of the principal amount to be redeemed, plus accrued and unpaid interest, and a “make-whole premium” with a value equal to the present value of the remaining scheduled interest payments of the 2022 Notes to be redeemed through May 1, 2022.

The Indenture contains customary terms and covenants, including that upon certain events of default occurring and continuing, either the trustee under the Indenture or the holders of not less than 25% in aggregate principal amount of the 2022 Notes then outstanding may declare the entire principal amount of all the notes, and the interest accrued on such notes, if any, to be immediately due and payable. In the case of certain events of bankruptcy, insolvency or reorganization relating to us or a principal subsidiary, the principal amount of the 2022 Notes together with any accrued and unpaid interest thereon will automatically be and become immediately due and payable.

In connection with the issuance of the 2022 Notes, we recorded a debt discount of $16.9 million as required under existing accounting rules. To arrive at this discount amount, we estimated the fair value of the liability component of the 2022 Notes as of October 26, 2016 using an income approach. To determine this estimated fair value, we used borrowing rates of similar market transactions involving comparable liabilities at the time of pricing and an expected life of 5.5 years. The effective interest rate for the 2022 Notes is 7.3% after considering the effect of the accretion of the related debt discount that represented the equity component of the 2022 Notes at their inception. We recorded $11.0 million, net of tax, related to the carrying amount of the equity component of the 2022 Notes. The remaining unamortized amount of the debt discount of the 2022 Notes was $16.5 million at December 31, 2016.

Convertible Senior Notes Due 2032

In March 2012, we completed a public offering and sale of our Convertible Senior Notes due 2032 (the “2032 Notes”) in the aggregate principal amount of $200 million. The 2032 Notes bear interest at a rate of 3.25% per annum, and are payable semi-annually in arrears on March 15 and September 15 of each year, beginning on September 15, 2012. The 2032 Notes mature on March 15, 2032, unless earlier converted, redeemed or repurchased. The 2032 Notes are convertible in certain circumstances and during certain periods at an initial conversion rate of 39.9752 shares of common stock per $1,000 principal amount (which represents an initial conversion price of approximately $25.02 per share of common stock), subject to adjustment in certain circumstances as set forth in the Indenture governing the 2032 Notes. We have the right and the intention to settle any such future conversions in cash.

Prior to March 20, 2018, the 2032 Notes are not redeemable. On or after March 20, 2018, we, at our option, may redeem some or all of the 2032 Notes in cash, at any time upon at least 30 days’ notice, at a price equal to 100% of the principal amount plus accrued and unpaid interest (including contingent interest, if any) up to but excluding the redemption date. In addition, the holders of the 2032 Notes may require us to purchase in cash some or all of their 2032 Notes at a repurchase price equal to 100% of the principal amount of the 2032 Notes, plus accrued and unpaid interest (including contingent interest, if any) up to but excluding the applicable repurchase date, on March 15, 2018, March 15, 2022 and March 15, 2027, or, subject to specified exceptions, at any time prior to the 2032 Notes’ maturity following a Fundamental Change (either a Change of Control or a Termination of Trading, as those terms are defined in the Indenture governing the 2032 Notes).

In connection with the issuance of the 2032 Notes, we recorded a debt discount of $35.4 million as required under existing accounting rules. To arrive at this discount amount, we estimated the fair value of the liability component of the 2032 Notes as of March 12, 2012 using an income approach. To determine this estimated fair value, we used borrowing rates of similar market transactions involving comparable liabilities at the time of pricing and an expected life of 6 years. In selecting the expected life, we selected the earliest date the holders could require us to repurchase all or a portion of the 2032 Notes (March 15, 2018). The effective interest rate for the 2032 Notes is 6.9% after considering the effect of the accretion of the related debt discount that represented the equity component of the 2032 Notes at their inception. We recorded $22.5 million, net of tax, related to the carrying amount of the equity component of the 2032 Notes. The remaining unamortized amount of the debt discount of the 2032 Notes was $2.6 million and $15.0 million at December 31, 2016 and 2015, respectively.

In June 2016, we repurchased $7.3 million in aggregate principal amount of the 2032 Notes for $6.5 million. In July 2016, we repurchased an additional $7.6 million in aggregate principal amount of the 2032 Notes for $7.0 million including $0.1 million in accrued interest. The purchase price reflects the market price of the notes at the time of purchase. In association with the issuance of the 2022 Notes in November 2016, we repurchased $125 million in aggregate principal amount of the 2032 Notes at par and paid $0.5 million in accrued interest. For the year ended December 31, 2016, we recognized a net loss of $3.5 million, which is presented as “Loss on repurchase of long-term debt” in the accompanying consolidated statement of operations. Included in the loss were charges totaling $7.5 million for the acceleration of a pro rata portion of unamortized debt discount and debt issuance costs related to the 2032 Notes, offset in part by $2.5 million related to the re-acquisition of the equity component of the 2032 Notes.

MARAD Debt

This U.S. government guaranteed financing (the “MARAD Debt”) is pursuant to Title XI of the Merchant Marine Act of 1936 administered by the Maritime Administration, and was used to finance the construction of the Q4000. The MARAD Debt is payable in equal semi-annual installments beginning in August 2002 and matures in February 2027. The MARAD Debt is collateralized by the Q4000, is guaranteed 50% by us, and initially bore interest at a floating rate that approximated AAA Commercial Paper yields plus 20 basis points. As required by the MARAD Debt agreements, in September 2005, we fixed the interest rate on the debt through the issuance of a 4.93% fixed-rate note with the same maturity date.

Nordea Credit Agreement

In September 2014, a wholly owned subsidiary incorporated in Luxembourg, Helix Q5000 Holdings S.à r.l. (“Q5000 Holdings”), entered into a credit agreement (the “Nordea Credit Agreement”) with a syndicated bank lending group for a term loan (the “Nordea Q5000 Loan”) in an amount of up to $250 million. The Nordea Q5000 Loan was funded in the amount of $250 million in April 2015 at the time the Q5000 vessel was delivered to us. The parent company of Q5000 Holdings, Helix Vessel Finance S.à r.l., also a wholly owned Luxembourg subsidiary, guaranteed the Nordea Q5000 Loan. The loan is secured by the Q5000 and its charter earnings as well as by a pledge of the shares of Q5000 Holdings. This indebtedness is non-recourse to Helix.

The Nordea Q5000 Loan bears interest at a LIBOR rate plus a margin of 2.5%. The Nordea Q5000 Loan matures on April 30, 2020 and is repayable in scheduled quarterly principal installments of $8.9 million with a balloon payment of $80.4 million at maturity. Q5000 Holdings may elect to prepay amounts outstanding under the Nordea Q5000 Loan without premium or penalty, but may not reborrow any amounts prepaid. Installment amounts are subject to adjustment for any prepayments on this debt. In June 2015, we entered into various interest rate swap contracts to fix the one-month LIBOR rate on a portion of our borrowings under the Nordea Q5000 Loan (Note 18). The total notional amount of the swaps (initially $187.5 million) decreases in proportion to the reduction in the principal amount outstanding under our Nordea Q5000 Loan. The fixed LIBOR rates are approximately 150 basis points.

The Nordea Credit Agreement and related loan documents include terms and conditions, including covenants and prepayment requirements, that are considered customary for this type of transaction. The covenants include restrictions on Q5000 Holdings’s ability to grant liens, incur indebtedness, make investments, merge or consolidate, sell or transfer assets, and pay dividends. In addition, the Nordea Credit Agreement obligates Q5000 Holdings to meet certain minimum financial requirements, including liquidity, consolidated debt service coverage and collateral maintenance.

Other

In accordance with our Credit Agreement, the 2032 Notes, the MARAD Debt agreements, and the Nordea Credit Agreement, we are required to comply with certain covenants, including certain financial ratios such as a consolidated interest coverage ratio and a consolidated leverage ratio, as well as the maintenance of minimum net worth, working capital and debt-to-equity requirements. As of December 31, 2016, we were in compliance with these covenants.

Scheduled maturities of long-term debt outstanding as of December 31, 2016 are as follows (in thousands):



	Term Loan			2022 Notes			2032 Notes ⁽¹⁾			MARAD Debt			Nordea Q5000 Loan			Total

Less than one year	$	25,634		$	—		$	—		$	6,222		$	35,715		$	67,571
One to two years	166,624			—			—			6,532			35,714			208,870
Two to three years	—			—			—			6,858			35,714			42,572
Three to four years	—			—			—			7,200			89,286			96,486
Four to five years	—			—			—			7,560			—			7,560
Over five years	—			125,000			60,115			48,850			—			233,965
Total debt	192,258			125,000			60,115			83,222			196,429			657,024
Current maturities	(25,634		)	—			—			(6,222		)	(35,715		)	(67,571		)
Long-term debt, less current maturities	166,624			125,000			60,115			77,000			160,714			589,453
Unamortized debt discounts ⁽²⁾	—			(16,513		)	(2,581		)	—			—			(19,094		)
Unamortized debt issuance costs ⁽³⁾	(1,391		)	(2,790		)	(231		)	(5,001		)	(2,550		)	(11,963		)
Long-term debt	$	165,233		$	105,697		$	57,303		$	71,999		$	158,164		$	558,396


(1)	Beginning in March 2018, the holders of the 2032 Notes may require us to repurchase these notes or we may at our option elect to repurchase these notes. The notes will mature in March 2032.


(2)	The 2022 Notes will increase to their face amount through accretion of non-cash interest charges through May 2022. The 2032 Notes will increase to their face amount through accretion of non-cash interest charges through March 2018.


(3)	Debt issuance costs are amortized over the term of the applicable debt agreement.

The following table details the components of our net interest expense (in thousands):



	Year Ended December 31,
	2016			2015			2014

Interest expense	$	45,110		$	40,024		$	33,064
Interest income	(2,086		)	(2,068		)	(4,786		)
Capitalized interest	(11,785		)	(11,042		)	(10,419		)
Net interest expense	$	31,239		$	26,914		$	17,859

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

We and our subsidiaries file a consolidated U.S. federal income tax return. We believe that our recorded deferred tax assets and liabilities are reasonable. However, tax laws and regulations are subject to interpretation and tax litigation is inherently uncertain, and therefore our assessments can involve a series of complex judgments about future events and rely heavily on estimates and assumptions.

Components of income tax provision (benefit) reflected in the consolidated statements of operations consist of the following (in thousands):



	Year Ended December 31,
	2016			2015			2014

Current	$	(27,319	)	$	1,832		$	43,817
Deferred	14,849			(103,022		)	23,154
	$	(12,470	)	$	(101,190	)	$	66,971



Domestic	$	(9,631	)	$	(102,978	)	$	29,613
Foreign	(2,839		)	1,788			37,358
	$	(12,470	)	$	(101,190	)	$	66,971

Components of income (loss) before income taxes are as follows (in thousands):



	Year Ended December 31,
	2016			2015			2014

Domestic	$	(61,484	)	$	(485,760	)	$	73,700
Foreign	(32,431		)	7,590			188,821
	$	(93,915	)	$	(478,170	)	$	262,521

Income taxes are provided based on the U.S. statutory rate of 35% and at the local statutory rate for each foreign jurisdiction adjusted for items that are allowed as deductions for federal and foreign income tax reporting purposes, but not for book purposes. The primary differences between the U.S. statutory rate and our effective rate are as follows:



	Year Ended December 31,
	2016		2015		2014

Statutory rate	35.0	%	35.0	%	35.0	%
Foreign provision	(5.1	)	(13.7	)	(9.1	)
Goodwill impairment	(16.8	)	—		—
Other	0.2		(0.1	)	(0.4	)
Effective rate	13.3	%	21.2	%	25.5	%

Deferred income taxes result from the effect of transactions that are recognized in different periods for financial and tax reporting purposes. The nature of these differences and the income tax effect of each are as follows (in thousands):



	December 31,
	2016			2015
Deferred tax liabilities:
Depreciation	$	192,777		$	173,863
Original issuance discount on 2022 Notes and 2032 Notes	11,802			17,957
Equity investments in production facilities	—			8,029
Prepaid and other	1,448			1,883
Total deferred tax liabilities	$	206,027		$	201,732
Deferred tax assets:
Net operating losses	$	(20,910	)	$	(23,595	)
Reserves, accrued liabilities and other	(38,131		)	(52,672		)
Total deferred tax assets	(59,041		)	(76,267		)
Valuation allowance	3,771			1,936
Net deferred tax liabilities	$	150,757		$	127,401
Deferred income tax is presented as:
Current deferred tax assets	$	(16,594	)	$	(53,573	)
Non-current deferred tax liabilities	167,351			180,974
Net deferred tax liabilities	$	150,757		$	127,401

At December 31, 2016, our U.S. net operating losses available for carryforward totaled $43.2 million and our foreign tax credits available for carryforward totaled $7.2 million. The net operating loss carryforward would expire in 2036 if unused. Foreign tax credits of $2.8 million and $4.4 million if unused would expire in 2025 and 2026, respectively. At December 31, 2016, the U.K. net operating losses of our well intervention company available for carryforward totaled $3.2 million. Realization is dependent on generating sufficient taxable income prior to expiration of the loss carryforwards. Although realization is not assured, management believes it is more likely than not that all of these tax attributes will be utilized. The amount of the deferred tax asset considered realizable, however, could be reduced in the near term if estimates of future taxable income during the carryforward are reduced.

At December 31, 2016, we had a $3.8 million valuation allowance related to certain non-U.S. deferred tax assets, primarily net operating losses generated in Brazil and from our oil and gas operations in the U.K., as management believes it is more likely than not that we will not be able to utilize the tax benefit. Additional valuation allowances may be made in the future if in management’s opinion it is more likely than not that the tax benefit will not be utilized.

We consider the undistributed earnings of our non-U.S. subsidiaries without operations in the U.S. to be permanently reinvested. At December 31, 2016 and 2015, our non-U.S. subsidiaries without operations in the U.S. had accumulated earnings and profits of approximately $74.9 million and $304.0 million, respectively. We have not provided deferred U.S. income tax on the accumulated earnings and profits from our non-U.S. subsidiaries without operations in the U.S. as we consider them permanently reinvested. Due to complexities in the tax laws and the manner of repatriation, it is not practicable to estimate the unrecognized amount of deferred income taxes and the related dividend withholding taxes associated with these undistributed earnings.

We account for tax-related interest in interest expense and tax penalties in selling, general and administrative expenses. No significant penalties or interest expense were accrued on our uncertain tax positions. We had unrecognized tax benefits of $0.3 million related to uncertain tax positions as of December 31, 2016, which if recognized would affect the annual effective tax rate. We had no uncertain tax positions as of December 31, 2015 and 2014. In 2014, in connection with the recognition of a $3.4 million tax benefit as a result of the completion of examination procedures for the 2006 through 2010 audit period by the U.S. Internal Revenue Service (see below), we reversed approximately $1.3 million of previously accrued interest and penalties.

A reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2016, 2015 and 2014 is as follows (in thousands):



	2016		2015		2014

Balance at January 1,	$	—	$	—	$	4,723
Additions for tax positions of prior years	343		—		—
Reductions for tax positions of prior years	—		—		(4,723		)
Balance at December 31,	$	343	$	—	$	—

We file tax returns in the U.S. and in various state, local and non-U.S. jurisdictions. We anticipate that any potential adjustments to our state, local and non-U.S. jurisdiction tax returns by taxing authorities would not have a material impact on our financial position. In June 2014, the Internal Revenue Service and the Joint Committee on Taxation completed the examination procedures including all appeals and administrative reviews that the taxing authorities are required and expected to perform for the 2006 through 2010 audit period, and in September 2014, we received an income tax refund in the amount of $35.2 million. The refund was primarily attributable to the utilization of a net operating loss carryback from 2010. In 2016, we received $28.4 million in U.S. and foreign income tax refunds for losses that were carried back to prior years. The tax periods from 2012 through 2016 remain open to review and examination by the Internal Revenue Service. In non-U.S. jurisdictions, the open tax periods include 2010 through 2016.

Shareholders' Equity

12 Months Ended

Dec. 31, 2016

Stockholders' Equity Note [Abstract]

Shareholders' Equity

Shareholders’ Equity

Our amended and restated Articles of Incorporation provide for authorized Common Stock of 240,000,000 shares with no stated par value per share and 5,000,000 shares of preferred stock, $0.01 par value per share issuable in one or more series.

On April 25, 2016, we launched an at-the-market (“ATM”) equity offering program and executed an Equity Distribution Agreement with Wells Fargo Securities, LLC (“Wells Fargo”) to sell up to $50 million of our common stock through Wells Fargo. As of December 31, 2016, we had sold a total of 6,309,355 shares of our common stock under this ATM program for $50 million, or an average of $7.92 per share. The proceeds from this ATM program totaled $47.7 million, net of transaction costs, including commissions of $1.3 million to Wells Fargo.

On August 11, 2016, we executed another Equity Distribution Agreement with Wells Fargo to sell an additional $50 million of our common stock under an ATM program. As of December 31, 2016, we had sold a total of 6,709,377 shares of our common stock under this ATM program for $50 million, or an average of $7.45 per share. The proceeds from this ATM program totaled $48.8 million, net of transaction costs, including commissions of $1.0 million to Wells Fargo.

Subsequently on January 10, 2017, we completed an underwritten public offering (the “Offering”) of 26,450,000 shares of our common stock, no par value, at a public offering price of $8.65 per share. The net proceeds from the Offering approximated $220 million, after deducting underwriting discounts and commissions and estimated offering expenses. We intend to use the net proceeds from the Offering for general corporate purposes, which may include debt repayment, capital expenditures, working capital, acquisitions or investments in our subsidiaries.

The components of Accumulated OCI are as follows (in thousands):



	December 31,
	2016			2015

Cumulative foreign currency translation adjustment	$	(78,953	)	$	(43,010	)
Unrealized loss on hedges, net ⁽¹⁾	(18,021		)	(27,891		)
Accumulated other comprehensive loss	$	(96,974	)	$	(70,901	)


(1)	Amounts relate to foreign currency hedges for the Grand Canyon, the Grand Canyon II and the Grand Canyon III charters as well as interest rate swap contracts for the Term Loan and the Nordea Q5000 Loan, and are net of deferred income taxes totaling $9.7 million and $15.1 million as of December 31, 2016 and 2015, respectively (Note 18).

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

Stock Buyback Program	12 Months Ended
Stock Buyback Program	Dec. 31, 2016
Equity [Abstract]
Stock Buyback Program	Stock Buyback Program Our Board of Directors has granted us the authority to repurchase shares of our common stock in an amount equal to any equity issued to our employees, officers and directors under our share-based compensation plans, including share-based awards issued under our existing long-term incentive plans and shares issued to our employees under our employee stock purchase plans (Note 12). We may continue to make repurchases pursuant to this authority from time to time as additional equity is issued under our stock based plans depending on prevailing market conditions and other factors. As described in an announced plan, all repurchases may be commenced or suspended at any time as determined by management. We have not purchased any shares available under this program since 2015. As of December 31, 2016, we had repurchased a total of 3,589,425 shares of our common stock. As of December 31, 2016, we had 2,327,608 shares of our common stock available for repurchase under the program.

Earnings Per Share

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Earnings Per Share

The computations of the numerator (income) and denominator (shares) to derive the basic and diluted EPS amounts presented on the face of the accompanying consolidated statements of operations are as follows (in thousands):



	Year Ended December 31,
	2016				2015				2014
	Income			Shares	Income			Shares	Income			Shares
Basic:
Net income (loss) applicable to common shareholders	$	(81,445	)		$	(376,980	)		$	195,047
Less: Undistributed earnings allocated to participating securities	—				—				(1,018		)
Undistributed earnings (loss) allocated to common shares	$	(81,445	)	111,612	$	(376,980	)	105,416	$	194,029		105,029



Diluted:
Undistributed earnings (loss) allocated to common shares	$	(81,445	)	111,612	$	(376,980	)	105,416	$	194,029	105,029
Effect of dilutive securities:
Share-based awards other than participating securities	—			—	—			—	—		16
Undistributed earnings reallocated to participating securities	—			—	—			—	—		—
Net income (loss) applicable to common shareholders	$	(81,445	)	111,612	$	(376,980	)	105,416	$	194,029	105,045

We had net losses for the years ended December 31, 2016 and 2015. Accordingly, our diluted EPS calculation for these periods was equivalent to our basic EPS calculation since diluted EPS excluded any assumed exercise or conversion of common stock equivalents. These common stock equivalents were excluded because they were deemed to be anti-dilutive, meaning their inclusion would have reduced the reported net loss per share in the applicable periods. Shares that otherwise would have been included in the diluted per share calculations assuming we had earnings are as follows (in thousands):



	Year Ended December 31,
	2016	2015

Diluted shares (as reported)	111,612	105,416
Share-based awards	440	59
Total	112,052	105,475

In addition, the following potentially dilutive shares related to the 2022 Notes and the 2032 Notes were excluded from the diluted EPS calculation because we have the right and the intention to settle any such future conversions in cash (Note 7) (in thousands):



	Year Ended December 31,
	2016	2015	2014

2022 Notes	1,475	—	—
2032 Notes	6,891	7,995	7,995

Employee Benefit Plans

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Employee Benefit Plans

Defined Contribution Plan

We sponsor a defined contribution 401(k) retirement plan covering substantially all of our employees. Our discretionary contributions are in the form of cash. Beginning in 2014, our matching contributions consisted of a 75% match of each employee’s contribution up to 5% of the employee’s salary. Our discretionary matching contributions were suspended for an indefinite period beginning February 2016. For the years ended December 31, 2016, 2015 and 2014, our costs related to the 401(k) plan totaled $0.5 million, $2.8 million and $2.2 million, respectively.

Employee Stock Purchase Plan

We have an employee stock purchase plan (the “ESPP”). The ESPP has 1.5 million shares authorized for issuance, of which 0.7 million shares were available for issuance as of December 31, 2016. Eligible employees who participate in the ESPP may purchase shares of our common stock through payroll deductions on an after-tax basis over a four-month period beginning on January 1, May 1, and September 1 of each year during the term of the ESPP, subject to certain restrictions and limitations established by the Compensation Committee of our Board of Directors and Section 423 of the Internal Revenue Code. The per share price of common stock purchased under the ESPP is equal to 85% of the lesser of (i) its fair market value on the first trading day of the purchase period or (ii) its fair market value on the last trading day of the purchase period. In February 2016, we suspended ESPP purchases for the January through April 2016 purchase period and indefinitely imposed a purchase limit of 130 shares per employee for subsequent purchase periods. For the years ended December 31, 2016, 2015 and 2014, share-based compensation with respect to the ESPP was $0.1 million, $1.1 million and $1.0 million, respectively.

Long-Term Incentive Stock-Based Plan

We currently have one active long-term incentive stock-based plan, the 2005 Long-Term Incentive Plan, as amended and restated effective January 1, 2017 (the “2005 Incentive Plan”). The 2005 Incentive Plan has 10.3 million shares authorized for issuance, which includes a maximum of 2.0 million shares that may be granted as incentive stock options. As of December 31, 2016, there were 3.7 million shares available for issuance under the 2005 Incentive Plan.

The 2005 Incentive Plan is administered by the Compensation Committee of our Board of Directors. The Compensation Committee also determines the type of award to be made to each participant and, as set forth in the related award agreement, the terms, conditions and limitations applicable to each award. The Compensation Committee may grant stock options, restricted stock, restricted stock units (“RSUs”), PSUs and cash awards. Awards granted under the 2005 Incentive Plan have a vesting period of three years (or 33% per year) with the exception of PSUs, which vest 100% on the three-year anniversary date of the grant.

The following grants of share-based awards were made in 2016 under the 2005 Incentive Plan:



Date of Grant	Shares	Grant Date Fair Value Per Share		Vesting Period

January 4, 2016 ⁽¹⁾	1,143,062	$	5.26	33% per year over three years
January 4, 2016 ⁽²⁾	1,143,062	$	7.13	100% on January 1, 2019
January 4, 2016 ⁽³⁾	11,763	$	5.26	100% on January 1, 2018
February 1, 2016 ⁽¹⁾	18,610	$	4.03	33% per year over three years
February 1, 2016 ⁽²⁾	18,610	$	7.13	100% on January 1, 2019
April 1, 2016 ⁽³⁾	13,727	$	5.60	100% on January 1, 2018
July 1, 2016 ⁽³⁾	8,476	$	6.76	100% on January 1, 2018
October 3, 2016 ⁽³⁾	7,803	$	8.13	100% on January 1, 2018
December 2, 2016 ⁽⁴⁾	94,680	$	11.09	33% per year over three years


(1)	Reflects the grant of restricted stock to our executive officers and select management employees.


(2)	Reflects the grant of PSUs to our executive officers and select management employees.


(3)	Reflects the grant of restricted stock to certain independent members of our Board of Directors who have made an election to take their quarterly fees in stock in lieu of cash.


(4)	Reflects annual equity grants to each independent member of our Board of Directors.

In January 2017, we granted our executive officers and select management employees 671,771 shares of restricted stock under the 2005 Incentive Plan. The market value of the restricted shares was $8.82 per share or $5.9 million. Concurrently, we issued our executive officers and the select management employees 671,771 PSUs under the 2005 Incentive Plan.

Restricted Stock

We grant restricted stock to members of our Board of Directors, executive officers and select management employees. The following table summarizes information about our restricted stock:



	Year Ended December 31,
	2016				2015				2014
	Shares		Grant Date Fair Value ⁽¹⁾		Shares		Grant Date Fair Value ⁽¹⁾		Shares		Grant Date Fair Value ⁽¹⁾

Awards outstanding at beginning of year	661,124		$	16.28	554,960		$	17.54	771,942		$	13.62
Granted	1,298,121		5.70		501,076		15.57		139,455		23.22
Vested ^{(2) (3)}	(305,588	)	16.94		(332,223	)	16.44		(356,437	)	11.27
Forfeited	(75,684	)	7.76		(62,689	)	20.93		—		—
Awards outstanding at end of year ⁽³⁾	1,577,973		$	7.86	661,124		$	16.28	554,960		$	17.54


(1)	Represents the weighted average grant date fair value, which is based on the quoted closing market price of our common stock on the trading day prior to the date of grant.


(2)	Total fair value of restricted stock and RSUs that vested during the years ended December 31, 2016, 2015 and 2014 was $2.2 million, $5.1 million and $8.2 million, respectively.


(3)	The vested and year-end amounts in 2014 each included 33,760 shares of RSUs with the grant date fair value of 15.80 per share. We paid $0.7 million in cash upon vesting of these RSUs in January 2015.

For the years ended December 31, 2016, 2015 and 2014, $5.8 million, $5.5 million and $5.0 million, respectively, were recognized as share-based compensation related to restricted stock and RSUs. Forfeitures on restricted stock totaled approximately 5% based on our most recent five-year average of historical forfeiture rates. Future compensation cost associated with unvested restricted stock at December 31, 2016 totaled approximately $7.5 million. The weighted average vesting period related to unvested restricted stock at December 31, 2016 was approximately 1.9 years.

Performance Share Units

We grant PSUs to our executive officers and select management employees. The PSUs provide for an award based on the performance of our common stock over a three-year period compared to the performance of other companies in a peer group selected by the Compensation Committee of our Board of Directors, with the maximum amount of the award being 200% of the original awarded PSUs and the minimum amount being zero. The vested PSUs may be settled in either cash or shares of our common stock at the discretion of the Compensation Committee of our Board of Directors with the exception of the PSUs granted in January 2017, which are to be settled solely in shares of our common stock.

We issued 1,161,672 PSUs in 2016 with a grant date fair value of $7.13 per unit, 295,693 PSUs in 2015 with a grant date fair value of $25.06 per unit and 73,609 PSUs in 2014 with a grant date fair value of $26.79 per unit. In January 2015, in connection with the vesting of the 2012 PSU awards, the decision was made by the Compensation Committee of our Board of Directors to settle these PSUs with a cash payment of $4.5 million (rather than with an equivalent number of shares of our common stock, which was the default payment method for the 2012 PSU awards). Accordingly, PSUs granted before 2017, including those that were previously accounted for as equity awards, are treated as liability awards. For the years ended December 31, 2016, 2015 and 2014, $6.8 million, $0.2 million and $5.4 million, respectively, were recognized as share-based compensation related to PSUs. For the years ended December 31, 2016 and 2015, $0.2 million and $2.9 million, respectively, were recorded in equity reflecting the cumulative compensation cost recognized in excess of the estimated fair value of the modified liability PSU awards. At December 31, 2016 and 2015, the liability balance for unvested PSUs was $7.1 million and $0.7 million, respectively. We paid $0.2 million to cash settle the 2013 grant of PSUs when they vested in January 2016. We paid $0.6 million to cash settle the 2014 grant of PSUs when they vested in January 2017.

Long-Term Incentive Cash Plans

We previously granted awards under certain long-term incentive cash plans (the “LTI Cash Plans”) that provide long-term cash-based compensation to eligible employees. These cash awards were generally indexed to our common stock with the payment amount at each vesting date, if any, determined by the performance of our common stock over the relevant performance period. Payout under these awards was calculated based on the ratio of the average stock price during the applicable measurement period over the original base price determined by the Compensation Committee of our Board of Directors at the time of the award. These cash awards vested equally each year over a three-year period and payments under these awards were made on each anniversary date of the award. The LTI Cash Plans are considered liability plans and as such are re-measured to fair value each reporting period with corresponding changes in the liability amount being reflected in our results of operations.

The cash awards granted under the LTI Cash Plans to our executive officers and select management employees totaled $8.9 million in 2014. No long-term incentive cash awards were granted subsequent to 2014. For the year ended December 31, 2014, total compensation cost associated with the cash awards issued pursuant to the LTI Cash Plans was $7.2 million ($3.6 million related to our executive officers). For the year ended December 31, 2015, we recorded reductions of $3.7 million ($2.1 million related to our executive officers) of previously recognized compensation cost associated with the cash awards issued pursuant to the LTI Cash Plans, reflecting the effect that decreases in our stock price had on the value of our liability plan. The liability balance for the cash awards issued under the LTI Cash Plans was less than $0.1 million at December 31, 2015. We reduced this liability balance down to zero at December 31, 2016 as these cash awards did not meet the performance requirements for any payout in January 2017. During 2014 and 2015, we paid $9.2 million and $8.9 million, respectively, of the liability associated with the LTI Cash Plans. No long-term incentive cash awards were paid in 2016.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Business Segment Information

12 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Business Segment Information

We have three reportable business segments: Well Intervention, Robotics and Production Facilities. Our U.S., U.K. and Brazil well intervention operating segments are aggregated into the Well Intervention business segment for financial reporting purposes. Our Well Intervention segment includes our vessels and equipment used to perform well intervention services primarily in the U.S. Gulf of Mexico, North Sea and Brazil. Our well intervention vessels include the Q4000, the Q5000, the Seawell, the Well Enhancer, and the chartered Skandi Constructor, Siem Helix 1 and Siem Helix 2 vessels. We previously owned the Helix 534, which we sold in December 2016 (Note 4). Our Well Intervention segment also includes IRSs, some of which we rent out on a stand-alone basis, and SILs. Our Robotics segment includes ROVs, trenchers and ROVDrills designed to complement offshore construction and well intervention services, and currently operates three chartered ROV support vessels. Our Production Facilities segment includes the HP I, the HFRS and our investment in Independence Hub that is accounted for under the equity method, and previously included our former ownership interest in Deepwater Gateway that we sold in February 2016 (Note 5). All material intercompany transactions between the segments have been eliminated.

We evaluate our performance based on operating income and income before income taxes of each reportable segment. Certain financial data by reportable segment are summarized as follows (in thousands):



	Year Ended December 31,
	2016			2015			2014
Net revenues —
Well Intervention	$	294,000		$	373,301		$	667,849
Robotics	160,580			301,026			420,224
Production Facilities	72,358			75,948			93,175
Other	—			—			358
Intercompany elimination	(39,356		)	(54,473		)	(74,450		)
Total	$	487,582		$	695,802		$	1,107,156



Income (loss) from operations —
Well Intervention ⁽¹⁾	$	14,910		$	(194,381	)	$	204,810
Robotics ⁽²⁾	(72,250		)	27,832			68,329
Production Facilities ⁽³⁾	33,861			(106,847		)	41,138
Corporate and other ⁽⁴⁾	(39,384		)	(33,866		)	(51,600		)
Intercompany elimination	(372		)	(98		)	(921		)
Total	$	(63,235	)	$	(307,360	)	$	261,756



	Year Ended December 31,
	2016			2015			2014
Net interest expense —
Well Intervention	$	(109	)	$	(102	)	$	(252	)
Robotics	(25		)	29			(5		)
Production Facilities	—			385			384
Corporate and elimination	31,373			26,602			17,732
Total	$	31,239		$	26,914		$	17,859



Equity in earnings (losses) of investments	$	(2,166	)	$	(124,345	)	$	879



Income (loss) before income taxes —
Well Intervention ⁽¹⁾	$	18,813		$	(193,572	)	$	211,725
Robotics ^{(2) (5)}	(73,533		)	2,454			61,025
Production Facilities ⁽³⁾	31,695			(231,577		)	41,633
Corporate and other and eliminations ^{(4) (6)}	(70,890		)	(55,475		)	(51,862		)
Total	$	(93,915	)	$	(478,170	)	$	262,521



Income tax provision (benefit) —
Well Intervention	$	12,531		$	(1,230	)	$	50,102
Robotics	(9,948		)	515			21,612
Production Facilities	11,093			(81,052		)	14,395
Corporate and other and eliminations	(26,146		)	(19,423		)	(19,138		)
Total	$	(12,470	)	$	(101,190	)	$	66,971



Capital expenditures —
Well Intervention	$	185,892		$	307,879		$	283,635
Robotics	720			10,700			51,348
Production Facilities	74			1,867			869
Corporate and other	(199		)	(135		)	1,060
Total	$	186,487		$	320,311		$	336,912



Depreciation and amortization —
Well Intervention	$	68,392	$	66,095	$	57,570
Robotics	25,848		26,724		24,478
Production Facilities	13,952		21,340		21,278
Corporate and eliminations	5,995		6,242		6,019
Total	$	114,187	$	120,401	$	109,345


(1)	Amount in 2016 included a $1.3 million gain on the sale of the Helix 534 in December 2016. Amount in 2015 included impairment charges of $205.2 million for the Helix 534 and $6.3 million for certain capitalized vessel project costs and a $16.4 million goodwill impairment charge related to our U.K. well intervention reporting unit.


(2)	Amount in 2016 included a $45.1 million goodwill impairment charge related to our robotics reporting unit.


(3)	Amount in 2015 included a $133.4 million impairment charge for the HP I.


(4)	Amount in 2014 included a $10.5 million gain on the sale of our Ingleside spoolbase in January 2014.


(5)	Amount in 2015 included unrealized losses totaling $18.3 million on our foreign currency exchange contracts associated with the Grand Canyon, Grand Canyon II and Grand Canyon III chartered vessels.


(6)	Amount in 2014 included $16.9 million of income with $7.2 million from an insurance reimbursement related to asset retirement work previously performed and the remaining from our overriding royalty income.

Intercompany segment amounts are derived primarily from equipment and services provided to other business segments at rates consistent with those charged to third parties. Intercompany segment revenues are as follows (in thousands):



	Year Ended December 31,
	2016		2015		2014

Well Intervention	$	8,442	$	22,855	$	29,875
Robotics	30,914		31,618		44,575
Total	$	39,356	$	54,473	$	74,450

Revenues by individually significant region are as follows (in thousands):



	Year Ended December 31,
	2016		2015		2014

United States	$	298,279	$	298,391	$	403,994
North Sea ⁽¹⁾	137,313		263,438		504,016
Other	51,990		133,973		199,146
Total	$	487,582	$	695,802	$	1,107,156


(1)	Includes revenues of $123.6 million, $187.7 million and $362.7 million, respectively, which were from the U.K.

Our assets related to operations, primarily our vessels, operate throughout the year in various regions around the world such as the U.S. Gulf of Mexico, North Sea, Asia Pacific and West Africa. The following table provides our property and equipment, net of accumulated depreciation, by individually significant geographic location of our assets (in thousands):



	December 31,
	2016		2015

United States	$	956,458	$	1,024,691
United Kingdom	299,699		352,740
Singapore ⁽¹⁾	194,649		112,313
Other	200,804		113,265
Total	$	1,651,610	$	1,603,009


(1)	Primarily includes the Q7000 vessel under construction.

Segment assets are comprised of all assets attributable to each reportable segment. Corporate and other includes all assets not directly identifiable with our business segments, most notably the majority of our cash and cash equivalents. The following table reflects total assets by reportable segment (in thousands):



	December 31,
	2016		2015

Well Intervention	$	1,596,517	$	1,484,109
Robotics	186,901		274,926
Production Facilities	158,192		182,007
Corporate and other	305,331		458,917
Total	$	2,246,941	$	2,399,959

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Commitments And Contingencies And Other Matters

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments And Contingencies And Other Matters

Commitments and Contingencies and Other Matters

Commitments

Commitments Related to Our Fleet

We have charter agreements for the Grand Canyon, Grand Canyon II and Grand Canyon III vessels for use in our robotics operations. We amended the charter agreements in February 2016 to reduce the charter rates and, in connection with such reductions, to extend the terms to October 2019 for the Grand Canyon, April 2021 for the Grand Canyon II and May 2023 for the Grand Canyon III. We also have a charter agreement for the Deep Cygnus which expires in March 2018.

In September 2013, we executed a contract with the same shipyard in Singapore that constructed the Q5000. This contract is for the construction of a newbuild semi-submersible well intervention vessel, the Q7000, which is being built to North Sea standards. This $346 million shipyard contract represents the majority of the expected costs associated with the construction of the Q7000. Pursuant to the original terms of this contract, 20% of the contract price was paid upon the signing of the contract. Pursuant to a contract amendment we entered into in June 2015, we agreed to pay the shipyard incremental costs of up to $14.5 million to extend the scheduled delivery of the Q7000 from mid-2016 to July 30, 2017 and to defer certain payment obligations. We paid $7.3 million of these costs in July 2015 and the remaining costs were to be paid upon the delivery of the vessel. Pursuant to a second contract amendment we entered into in December 2015, the remaining 80% is to be paid in three installments, with 20% in June 2016 (payment was made in October 2016 as agreed between the parties), 20% upon issuance of the Completion Certificate, which is to be issued on or before December 31, 2017, and 40% upon the delivery of the vessel, which at our option can be deferred until December 30, 2018. Also pursuant to this second amendment, we agreed to reimburse the shipyard for incremental costs in connection with the further deferment of the Q7000’s delivery. Incremental costs are capitalized as they are incurred during the construction of the vessel. At December 31, 2016, our total investment in the Q7000 was $194.6 million, including $69.2 million paid to the shipyard upon signing the contract and the $69.2 million installment payment in October 2016.

In February 2014, we entered into agreements with Petróleo Brasileiro S.A. (“Petrobras”) to provide well intervention services offshore Brazil, and in connection with the Petrobras agreements, we entered into charter agreements with Siem Offshore AS (“Siem”) for two newbuild monohull vessels, the Siem Helix 1 and the Siem Helix 2. The initial term of the charter agreements with Siem is for seven years from the respective vessel delivery dates with options to extend. The initial term of the agreements with Petrobras is for four years with Petrobras’s options to extend. As part of Petrobras’s efforts to reduce its costs structure with many of its suppliers, we and Petrobras began discussions in mid-2015 with respect to potentially amending our contracts in a manner that addressed Petrobras’s objectives and was acceptable to us as well. Those negotiations were finalized in early June 2016 such that the contracts for the Siem Helix 1, originally scheduled to begin no later than July 22, 2016, were amended to commence between July 22, 2016 and October 21, 2016, with the day rate reduced to a mutually acceptable level, and the contracts for the Siem Helix 2, originally scheduled to begin no later than January 21, 2017, were amended to commence between October 1, 2017 and December 31, 2017, with no change in the day rate.

The Siem Helix 1 vessel was delivered to us and the charter term began on June 14, 2016. The vessel has transited to Brazil after integration and commissioning of our topside equipment onboard. The Siem Helix 1 is continuing to work through Petrobras’s inspection and acceptance process, including the completion of modifications as agreed between us and Petrobras. Our current expectation is that the vessel will commence operations before the end of the first quarter of 2017. The Siem Helix 2 was delivered to us and the charter term began on February 10, 2017. We are currently integrating and commissioning our topside equipment onboard the vessel, and we anticipate that the vessel will be available for work in the second quarter of 2017 prior to commencing services for Petrobras in the fourth quarter of 2017. At December 31, 2016, our total investment in the topside equipment for the two vessels was $200.7 million. In November 2014, we paid a charter fee deposit of $12.5 million, which will be used to reduce our final charter payments for the Siem Helix 2.

Lease Commitments

We lease facilities and charter vessels under non-cancelable operating leases and vessel charters expiring at various dates through 2031. Future minimum rentals at December 31, 2016 are as follows (in thousands):



	Vessels		Facilities and Other		Total

2017	$	156,446	$	5,788	$	162,234
2018	142,407		5,163		147,570
2019	131,665		5,123		136,788
2020	111,650		4,753		116,403
2021	99,563		4,667		104,230
Thereafter	149,861		19,566		169,427
Total lease commitments	$	791,592	$	45,060	$	836,652

For the years ended December 31, 2016, 2015 and 2014, total rental expense was approximately $87.8 million, $134.3 million and $147.2 million, respectively.

We sublease some of our facilities under non-cancelable sublease agreements. For the years ended December 31, 2016, 2015 and 2014, total rental income was $1.6 million, $1.4 million and $0.8 million, respectively. As of December 31, 2016, the minimum rentals to be received in the future totaled $2.0 million.

In January 2016, we entered into an agreement to lease back our former office and warehouse property located in Aberdeen, Scotland for 15 years with two five-year options to extend the lease. The annual minimum lease payment is approximately $0.8 million.

Contingencies and Claims

We believe that there are currently no contingencies that would have a material adverse effect on our financial position, results of operations and cash flows.

Litigation

On July 31, 2015, a purported stockholder, Parviz Izadjoo, filed a class action lawsuit styled Parviz Izadjoo v. Owen Kratz and Helix Energy Solutions Group, Inc. against the Company and Mr. Kratz, our President and Chief Executive Officer, in the United States District Court for the Southern District of Texas on behalf of a putative class of all purchasers of shares of our common stock between October 21, 2014, and July 21, 2015, inclusive (the “Class Period”). The lawsuit asserted violations of Section 10(b) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and SEC Rule 10b-5 as to both us and Mr. Kratz, and Section 20(a) of the Exchange Act against Mr. Kratz, based on alleged misrepresentations and omissions in SEC filings and other public disclosures regarding projections for 2015 dry docks of two of our vessels working in the Gulf of Mexico that allegedly caused the price at which putative class members bought stock during the proposed class period to be artificially inflated. On January 28, 2016, the judge in the case approved a motion for the appointment of lead plaintiff and lead counsel. On March 14, 2016, the plaintiffs filed an amended class action complaint, adding Mr. Tripodo (our Executive Vice President and Chief Financial Officer) and Mr. Chamblee (our former Executive Vice President and Chief Operating Officer) as individual defendants, alleging the same types of claims made in the original complaint (alleged violations during the Class Period of Section 10(b) of the Exchange Act and SEC Rule 10b-5 with respect to all defendants, and Section 20(a) of the Exchange Act against the individual defendants), but asserting that the alleged misrepresentations and omissions in SEC filings and other public disclosures are related to the condition of and repairs to certain equipment aboard the Q4000 vessel. The defendants filed a motion to dismiss on April 28, 2016, and on February 14, 2017, the defendants’ motion to dismiss the complaint was granted. The dismissal was without prejudice, with leave for plaintiff to amend the complaint by no later than March 17, 2017.

We are involved in various other legal proceedings, some involving claims for personal injury under the General Maritime Laws of the United States and the Jones Act based on alleged negligence. In addition, from time to time we incur other claims, such as contract disputes, in the normal course of business.

Statement Of Cash Flow Information

12 Months Ended

Dec. 31, 2016

Supplemental Cash Flow Information [Abstract]

Statement Of Cash Flow Information

Statement of Cash Flow Information

The following table provides supplemental cash flow information (in thousands):



	Year Ended December 31,
	2016		2015		2014

Interest paid, net of interest capitalized	$	18,749	$	14,555	$	11,628
Income taxes paid	5,635		16,905		70,509

Our non-cash investing activities include property and equipment capital expenditures that are incurred but not yet paid. As of December 31, 2016 and 2015, these non-cash capital expenditures totaled $10.1 million and $18.7 million, respectively. Additionally, our non-cash investing activities for the year ended December 31, 2014 included a $27.5 million non-cash transaction related to the promissory note we received in connection with the sale of our Ingleside spoolbase in January 2014 (Note 4).

Allowance Accounts

12 Months Ended

Dec. 31, 2016

Valuation and Qualifying Accounts [Abstract]

Allowance Accounts

The following table sets forth the activity in our valuation accounts for each of the three years in the period ended December 31, 2016 (in thousands):



	Allowance for Uncollectible Accounts			Deferred Tax Asset Valuation Allowance

Balance at December 31, 2013	$	2,234		$	22,860
Additions ⁽¹⁾	5,331			—
Deductions ⁽²⁾	(2,830		)	—
Adjustments	—			216
Balance at December 31, 2014	4,735			23,076
Additions ⁽¹⁾	3,275			—
Deductions ⁽²⁾	(7,660		)	—
Adjustments ⁽³⁾	—			(21,140		)
Balance at December 31, 2015	350			1,936
Additions ⁽¹⁾	1,778			—
Deductions ⁽²⁾	(350		)	—
Adjustments ⁽⁴⁾	—			1,835
Balance at December 31, 2016	$	1,778		$	3,771


(1)	The increase in allowance for uncollectible accounts primarily reflects charges associated with the provision for uncertain collection of a portion of our existing trade receivables related to our Robotics segment.


(2)	The decrease in allowance for uncollectible accounts reflects the write-offs of trade receivables that are either settled or deemed uncollectible.


(3)	The decrease in valuation allowance primarily reflects a $20.6 million reduction related to the loss of deferred tax assets for net operating losses within our Australian subsidiaries.


(4)	The increase in valuation allowance primarily reflects additional net operating losses in Brazil for which insufficient future taxable income exists to offset the losses.

Our allowance accounts as of December 31, 2016 also included $4.2 million related to a non-current note receivable (Note 3). See Note 2 for a detailed discussion regarding our accounting policy on accounts and notes receivable and allowance for uncollectible accounts and Note 8 for a detailed discussion of the valuation allowance related to our deferred tax assets.

Fair Value Measurements

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements

Assets and liabilities measured at fair value are based on one or more of three valuation approaches as follows:


(a)	Market Approach. Prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities.


(b)	Cost Approach. Amount that would be required to replace the service capacity of an asset (replacement cost).


(c)	Income Approach. Techniques to convert expected future cash flows to a single present amount based on market expectations (including present value techniques, option-pricing and excess earnings models).

Our financial instruments include cash and cash equivalents, receivables, accounts payable, long-term debt and various derivative instruments. The carrying amount of cash and cash equivalents, trade and other current receivables as well as accounts payable approximates fair value due to the short-term nature of these instruments. The net carrying amount of our long-term note receivable also approximates its fair value. The following tables provide additional information relating to other financial instruments measured at fair value on a recurring basis (in thousands):



	Fair Value Measurements at December 31, 2016 Using								Valuation Approach
	Level 1		Level 2 ⁽¹⁾		Level 3		Total		Valuation Approach
Assets:
Interest rate swaps	$	—	$	451	$	—	$	451	(c)

Liabilities:
Foreign exchange contracts	—		38,170		—		38,170		(c)
Interest rate swaps	—		751		—		751		(c)
Total net liability	$	—	$	38,470	$	—	$	38,470



	Fair Value Measurements at December 31, 2015 Using								Valuation Approach
	Level 1		Level 2 ⁽¹⁾		Level 3		Total		Valuation Approach
Assets:
Interest rate swaps	$	—	$	413	$	—	$	413	(c)

Liabilities:
Foreign exchange contracts	—		61,427		—		61,427		(c)
Interest rate swaps	—		1,473		—		1,473		(c)
Total net liability	$	—	$	62,487	$	—	$	62,487

(1)

Unless otherwise indicated, the fair value of our Level 2 derivative instruments reflects our best estimate and is based upon exchange or over-the-counter quotations whenever they are available. Quoted valuations may not be available due to location differences or terms that extend beyond the period for which quotations are available. Where quotes are not available, we utilize other valuation techniques or models to estimate market values. These modeling techniques require us to make estimations of future prices, price correlation and market volatility and liquidity based on market data. Our actual results may differ from our estimates, and these differences could be positive or negative. See Note 18 for further discussion on fair value of our derivative instruments.

The carrying values and estimated fair values of our long-term debt are as follows (in thousands):



	December 31,
	2016				2015
	Carrying Value ⁽¹⁾		Fair Value ⁽²⁾		Carrying Value ⁽¹⁾		Fair Value ⁽²⁾

Term Loan (matures June 2018)	$	192,258	$	192,258	$	255,000	$	248,467
Nordea Q5000 Loan (matures April 2020)	196,429		192,746		232,143		221,553
MARAD Debt (matures February 2027)	83,222		92,049		89,148		104,897
2022 Notes (mature May 2022)	125,000		130,156		—		—
2032 Notes (mature March 2032)	60,115		59,965		200,000		150,250
Total debt	$	657,024	$	667,174	$	776,291	$	725,167


(1)	Carrying value includes current maturities and excludes the related unamortized debt discount and debt issuance costs. See Note 7 for additional disclosures on our long-term debt.

(2)

The estimated fair value of the 2022 Notes and the 2032 Notes was determined using Level 1 inputs under the market approach. The fair value of the Term Loan, the Nordea Q5000 Loan and the MARAD Debt was estimated using Level 2 fair value inputs under the market approach. The fair value of the Term Loan, the Nordea Q5000 Loan and the MARAD Debt was determined using a third party evaluation of the remaining average life and outstanding principal balance of the indebtedness as compared to other obligations in the marketplace with similar terms.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Derivative Instruments And Hedging Activities

12 Months Ended

Dec. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments And Hedging Activities

Derivative Instruments and Hedging Activities

The following table presents the balance sheet location and fair value of our derivative instruments that were designated as hedging instruments (in thousands):



	December 31,
	2016			2015
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Asset Derivative Instruments:
Interest rate swaps	Other assets, net	$	451	Other assets, net	$	413
		$	451		$	413

Liability Derivative Instruments:
Foreign exchange contracts	Accrued liabilities	$	14,056	Accrued liabilities	$	14,955
Interest rate swaps	Accrued liabilities	751		Accrued liabilities	1,473
Foreign exchange contracts	Other non-current liabilities	13,383		Other non-current liabilities	28,458
		$	28,190		$	44,886

The following table presents the balance sheet location and fair value of our derivative instruments that were not designated as hedging instruments (in thousands):



	December 31,
	2016			2015
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Liability Derivative Instruments:
Foreign exchange contracts	Accrued liabilities	$	3,923	Accrued liabilities	$	6,763
Foreign exchange contracts	Other non-current liabilities	6,808		Other non-current liabilities	11,251
		$	10,731		$	18,014

In January 2013, we entered into foreign currency exchange contracts to hedge through September 2017 the foreign currency exposure associated with the Grand Canyon charter payments ($104.6 million) denominated in Norwegian kroner (NOK591.3 million). In February 2013, we entered into similar foreign currency exchange contracts to hedge our foreign currency exposure with respect to the Grand Canyon II and Grand Canyon III charter payments ($100.4 million and $98.8 million, respectively) denominated in Norwegian kroner (NOK594.7 million and NOK595.0 million, respectively), through July 2019 and February 2020, respectively.

During discussions with the owner of the Grand Canyon, Grand Canyon II and Grand Canyon III vessels with respect to amending the charter agreements, it became apparent in December 2015 that a portion of previously forecasted charter payments in NOK would no longer be made. We concluded that the foreign currency exchange contracts associated with the charter payments for the Grand Canyon still qualified for cash flow hedge accounting treatment. However, the foreign currency exchange contracts associated with the charter payments for the Grand Canyon II and Grand Canyon III vessels no longer qualified as cash flow hedges. As a result, we de-designated these hedges and re-designated the hedging relationship between a portion of our foreign currency exchange contracts and our forecasted Grand Canyon II and Grand Canyon III charter payments of NOK434.1 million and NOK185.2 million, respectively, that were expected to remain highly probable of occurring. Our Accumulated OCI (net of tax) as of December 31, 2015 included unrealized losses of $19.8 million associated with the re-designated foreign currency exchange contracts that qualify for hedge accounting treatment. We recognized unrealized losses of $18.0 million related to the foreign currency exchange contracts associated with the portion of previously forecasted charter payments that would no longer be made. Reflected in “Other income (expense), net” in the accompanying consolidated statement of operations are these unrealized losses, as well as subsequent changes in unrealized losses associated with the foreign currency exchange contracts that are no longer designated as cash flow hedges.

Hedge ineffectiveness also is reflected in “Other income (expense), net” in the accompanying consolidated statement of operations. For the year ended December 31, 2016, we recorded realized gains of $0.1 million related to the Grand Canyon hedge ineffectiveness. There were no unrealized gains or losses associated with hedge ineffectiveness. For the year ended December 31, 2015, we recorded realized losses of $3.6 million related to the Grand Canyon II and Grand Canyon III hedge ineffectiveness and unrealized losses of $1.5 million related to the Grand Canyon hedge ineffectiveness. For the year ended December 31, 2014, we recorded realized losses of $0.5 million and unrealized losses of $1.2 million related to the Grand Canyon II hedge ineffectiveness.

In September 2013, we entered into various interest rate swap contracts to fix the interest rate on $148.1 million of our Term Loan borrowings (Note 7). The term of these swap contracts, which were settled monthly, expired in October 2016. Additionally, in June 2015 we entered into various interest rate swap contracts to fix the interest rate on $187.5 million of our Nordea Q5000 Loan borrowings (Note 7). These swap contracts, which are settled monthly, began in June 2015 and extend through April 2020. Our interest rate swap contracts qualify for cash flow hedge accounting treatment. The amount of ineffectiveness associated with our interest rate swap contracts was immaterial for all periods presented.

The following tables present the impact that derivative instruments designated as hedging instruments had on our Accumulated OCI (net of tax) and our consolidated statements of operations (in thousands). We estimate that as of December 31, 2016, $9.6 million of losses in Accumulated OCI associated with our derivative instruments is expected to be reclassified into earnings within the next 12 months.



	Gain (Loss) Recognized in OCI on Derivative Instruments, Net of Tax (Effective Portion)
	Year Ended December 31,
	2016		2015			2014

Foreign exchange contracts	$	9,397	$	4,734		$	(22,170	)
Interest rate swaps	473		(534		)	70
	$	9,870	$	4,200		$	(22,100	)



	Location of Loss Reclassified from Accumulated OCI into Earnings	Loss Reclassified from Accumulated OCI into Earnings (Effective Portion)
		Year Ended December 31,
		2016			2015			2014

Foreign exchange contracts	Cost of sales	$	(10,827	)	$	(11,516	)	$	(2,507	)
Interest rate swaps	Net interest expense	(2,024		)	(2,143		)	(858		)
		$	(12,851	)	$	(13,659	)	$	(3,365	)

The following table presents the impact that derivative instruments not designated as hedging instruments had on our consolidated statements of operations (in thousands):



	Location of Gain (Loss) Recognized in Earnings on Derivative Instruments	Gain (Loss) Recognized in Earnings on Derivative Instruments
		Year Ended December 31,
		2016		2015			2014

Foreign exchange contracts	Other income (expense), net	$	1,198	$	(18,014	)	$	7
		$	1,198	$	(18,014	)	$	7

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

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+ Details

Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information (Unaudited)

Offshore marine construction activities may fluctuate as a result of weather conditions as well as the timing of capital expenditures by oil and gas companies. Historically, a substantial portion of our services has been performed during the summer and fall months. As a result, historically a disproportionate portion of our revenues and net income is earned during such period. The following is a summary of consolidated quarterly financial information (in thousands, except per share amounts):



	Quarter Ended
	March 31,			June 30,			September 30,		December 31,
2016
Net revenues	$	91,039		$	107,267		$	161,245	$	128,031
Gross profit (loss)	(16,930		)	5,658			40,184		17,604
Net income (loss) applicable to common shareholders ⁽¹⁾	(27,823		)	(10,671		)	11,462		(54,413		)
Basic earnings (loss) per common share	$	(0.26	)	$	(0.10	)	$	0.10	$	(0.46	)
Diluted earnings (loss) per common share	$	(0.26	)	$	(0.10	)	$	0.10	$	(0.46	)



	Quarter Ended
	March 31,		June 30,			September 30,		December 31,
2015
Net revenues	$	189,641	$	166,016		$	182,462	$	157,683
Gross profit (loss) ⁽²⁾	34,947		24,208			31,969		(324,898		)
Net income (loss) applicable to common shareholders ⁽³⁾	19,642		(2,635		)	9,880		(403,867		)
Basic earnings (loss) per common share	$	0.19	$	(0.03	)	$	0.09	$	(3.83	)
Diluted earnings (loss) per common share	$	0.19	$	(0.03	)	$	0.09	$	(3.83	)


(1)	Amount in the fourth quarter of 2016 included a $45.1 million goodwill impairment charge related to our robotics reporting unit (Notes 2 and 6).


(2)	Amount in the fourth quarter of 2015 included impairment charges of $205.2 million for the Helix 534 and $133.4 million for the HP I and $6.3 million for certain capitalized vessel project costs (Note 4).

(3)

Amount in the fourth quarter of 2015 included a $16.4 million goodwill impairment charge related to our U.K. well intervention reporting unit (Notes 2 and 6), losses totaling $123.8 million related to our equity investments in Deepwater Gateway and Independence Hub (Note 5), and unrealized losses totaling $19.0 million on our foreign currency exchange contracts associated with the Grand Canyon, Grand Canyon II and Grand Canyon III chartered vessels (Note 18).

Summary Of Significant Accounting Policies (Policy)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Principles of Consolidation

Basis of Presentation

Use of Estimates

Cash and Cash Equivalents

Cash and cash equivalents are highly liquid financial instruments with original maturities of three months or less. They are carried at cost plus accrued interest, which approximates fair value.

Accounts and Notes Receivable and Allowance for Uncollectible Accounts

Property and Equipment

Capitalized Interest

Equity Investments

Goodwill

Recertification Costs and Deferred Dry Dock Charges

Recertification Costs and Deferred Dry Dock Costs

Revenue Recognition


•	the customer provides specifications for the provision of services;


•	we can reasonably estimate our progress towards completion and our costs;


•	the contract includes provisions for enforceable rights regarding the goods or services to be provided, consideration to be received, and the manner and terms of payment;


•	the customer can be expected to satisfy its obligations under the contract; and


•	we can be expected to perform our contractual obligations.

Revenue from Royalty Interests

Income Taxes

Share-Based Compensation

Foreign Currency

Derivative Instruments and Hedging Activities

Interest Rate Risk

Foreign Currency Exchange Rate Risk

Earnings Per Share

Major Customers and Concentration of Credit Risk

Fair Value Measurements


•	Level 1. Observable inputs such as quoted prices in active markets;


•	Level 2. Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and


•	Level 3. Unobservable inputs for which there is little or no market data, which require the reporting entity to develop its own assumptions.

Assets and liabilities measured at fair value are based on one or more of three valuation approaches as described in Note 17.

Asset Retirement Obligations

New Accounting Standards

We do not expect any other recent accounting standards to have a material impact on our financial position, results of operations or cash flows.

Details Of Certain Accounts (Tables)

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of other current assets

Other current assets consist of the following (in thousands):



	December 31,
	2016		2015

Note receivable (Note 4)	$	10,000	$	10,000
Prepaid insurance	4,426		5,433
Other prepaids	9,547		10,142
Deferred costs	7,971		609
Spare parts inventory	2,548		4,985
Income tax receivable	880		—
Value added tax receivable	1,345		7,842
Other	671		507
Total other current assets	$	37,388	$	39,518

Schedule of other assets, net

Other assets, net consist of the following (in thousands):



	December 31,
	2016		2015

Note receivable, net ⁽¹⁾	$	2,827	$	—
Prepaids	6,418		—
Deferred dry dock costs, net (Note 2)	14,766		19,615
Deferred costs ⁽²⁾	30,738		—
Deferred financing costs, net ⁽³⁾	3,745		7,863
Charter fee deposit (Note 14)	12,544		12,544
Other	1,511		1,586
Total other assets, net	$	72,549	$	41,608


(1)	Amount, net of allowance of $4.2 million, relates to an agreement we entered into with one of our customers to defer their payment obligations until June 30, 2018. Interest at a rate of 3% per annum is payable semi-annually.


(2)	Amount relates to deferred mobilization costs (Note 2).


(3)	Represents unamortized debt issuance costs related to our Revolving Credit Facility (Note 7).

Schedule of accrued liabilities

Accrued liabilities consist of the following (in thousands):



	December 31,
	2016		2015

Accrued payroll and related benefits	$	20,705	$	14,775
Deferred revenue	8,911		12,841
Accrued interest	3,758		4,854
Derivative liability (Note 18)	18,730		23,192
Taxes payable excluding income tax payable	1,214		8,136
Other	5,296		7,843
Total accrued liabilities	$	58,614	$	71,641

Schedule of other non-current liabilities

Other non-current liabilities consist of the following (in thousands):



	December 31,
	2016		2015

Investee losses in excess of investment (Note 5)	$	10,238	$	8,308
Deferred gain on sale of property (Note 4)	5,761		—
Deferred revenue	8,598		—
Derivative liability (Note 18)	20,191		39,709
Other	8,197		3,398
Total other non-current liabilities	$	52,985	$	51,415

Property And Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Summary of gross components of property and equipment

The following is a summary of the gross components of property and equipment (dollars in thousands):



		December 31,
	Estimated Useful Life	2016		2015

Vessels	15 to 30 years	$	1,860,379	$	1,944,753
ROVs, trenchers and ROVDrills	10 years	309,603		311,971
Machinery, equipment, buildings and leasehold improvements	5 to 30 years	280,908		288,133
Total property and equipment		$	2,450,890	$	2,544,857

Equity Investments (Tables)

12 Months Ended

Dec. 31, 2016

Equity Method Investments and Joint Ventures [Abstract]

Schedule of distributions from equity method investments

We received the following distributions from our equity method investments (in thousands):



	Year Ended December 31,
	2016		2015		2014

Deepwater Gateway	$	1,200	$	5,200	$	6,150
Independence Hub	—		1,800		2,640
Total	$	1,200	$	7,000	$	8,790

Summary financial information related to equity method investments

The summarized aggregated financial information related to our equity method investments for 2014 and 2015 is as follows (in thousands):



	Year Ended December 31,
	2015			2014

Revenues	$	14,791		$	23,284
Operating income (loss)	(448,138		)	411
Net income (loss)	(448,138		)	411



	December 31,
	2015

Current assets	$	3,181
Non-current assets	70,812
Current liabilities	180
Non-current liabilities	62,951

Goodwill (Tables)

12 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in carrying amount of goodwill

The changes in the carrying amount of goodwill are as follows (in thousands):



	Well Intervention			Robotics			Total

Balance at December 31, 2014	$	17,039		$	45,107		$	62,146
Impairment loss	(16,399		)	—			(16,399		)
Other adjustments ⁽¹⁾	(640		)	—			(640		)
Balance at December 31, 2015	—			45,107			45,107
Impairment loss	—			(45,107		)	(45,107		)
Balance at December 31, 2016	$	—		$	—		$	—


(1)	Reflects foreign currency adjustment related to the goodwill of our U.K. well intervention reporting unit.

Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of long-term debt

Long-term debt consists of the following (in thousands):



	December 31,
	2016			2015

Term Loan (matures June 2018)	$	192,258		$	255,000
2022 Notes (mature May 2022)	125,000			—
2032 Notes (mature March 2032)	60,115			200,000
MARAD Debt (matures February 2027)	83,222			89,148
Nordea Q5000 Loan (matures April 2020)	196,429			232,143
Unamortized debt discounts	(19,094		)	(14,963		)
Unamortized debt issuance costs	(11,963		)	(11,993		)
Total debt	625,967			749,335
Less current maturities	(67,571		)	(71,640		)
Long-term debt	$	558,396		$	677,695

Schedule of debt covenants

Also pursuant to the February 2016 amendment to the Credit Agreement,


(a)	The minimum permitted Consolidated Interest Coverage Ratio was revised as follows:



Four Fiscal Quarters Ending	Minimum Consolidated Interest Coverage Ratio

December 31, 2016 through and including March 31, 2017	2.75	to 1.00
June 30, 2017 and each fiscal quarter thereafter	3.00	to 1.00


(b)	The maximum permitted Consolidated Leverage Ratio was revised as follows:



Four Fiscal Quarters Ending	Maximum Consolidated Leverage Ratio

December 31, 2016	5.00	to 1.00
March 31, 2017	4.75	to 1.00
June 30, 2017	4.25	to 1.00
September 30, 2017	3.75	to 1.00
December 31, 2017 and each fiscal quarter thereafter	3.50	to 1.00

(c)



Consolidated Leverage Ratio	Minimum Cash Balance

Greater than or equal to 4.50x	$150,000,000.00
Greater than or equal to 4.00x but less than 4.50x	100,000,000.00
Greater than or equal to 3.50x but less than 4.00x	50,000,000.00
Less than 3.50x	0.00

Schedule of maturities of long-term debt outstanding

Scheduled maturities of long-term debt outstanding as of December 31, 2016 are as follows (in thousands):



	Term Loan			2022 Notes			2032 Notes ⁽¹⁾			MARAD Debt			Nordea Q5000 Loan			Total

Less than one year	$	25,634		$	—		$	—		$	6,222		$	35,715		$	67,571
One to two years	166,624			—			—			6,532			35,714			208,870
Two to three years	—			—			—			6,858			35,714			42,572
Three to four years	—			—			—			7,200			89,286			96,486
Four to five years	—			—			—			7,560			—			7,560
Over five years	—			125,000			60,115			48,850			—			233,965
Total debt	192,258			125,000			60,115			83,222			196,429			657,024
Current maturities	(25,634		)	—			—			(6,222		)	(35,715		)	(67,571		)
Long-term debt, less current maturities	166,624			125,000			60,115			77,000			160,714			589,453
Unamortized debt discounts ⁽²⁾	—			(16,513		)	(2,581		)	—			—			(19,094		)
Unamortized debt issuance costs ⁽³⁾	(1,391		)	(2,790		)	(231		)	(5,001		)	(2,550		)	(11,963		)
Long-term debt	$	165,233		$	105,697		$	57,303		$	71,999		$	158,164		$	558,396


(1)	Beginning in March 2018, the holders of the 2032 Notes may require us to repurchase these notes or we may at our option elect to repurchase these notes. The notes will mature in March 2032.


(2)	The 2022 Notes will increase to their face amount through accretion of non-cash interest charges through May 2022. The 2032 Notes will increase to their face amount through accretion of non-cash interest charges through March 2018.


(3)	Debt issuance costs are amortized over the term of the applicable debt agreement.

Components of net interest expense

The following table details the components of our net interest expense (in thousands):



	Year Ended December 31,
	2016			2015			2014

Interest expense	$	45,110		$	40,024		$	33,064
Interest income	(2,086		)	(2,068		)	(4,786		)
Capitalized interest	(11,785		)	(11,042		)	(10,419		)
Net interest expense	$	31,239		$	26,914		$	17,859

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of components of income tax provision (benefit) on continuing operations

Components of income tax provision (benefit) reflected in the consolidated statements of operations consist of the following (in thousands):



	Year Ended December 31,
	2016			2015			2014

Current	$	(27,319	)	$	1,832		$	43,817
Deferred	14,849			(103,022		)	23,154
	$	(12,470	)	$	(101,190	)	$	66,971



Domestic	$	(9,631	)	$	(102,978	)	$	29,613
Foreign	(2,839		)	1,788			37,358
	$	(12,470	)	$	(101,190	)	$	66,971

Schedule of components of income (loss) before income taxes

Components of income (loss) before income taxes are as follows (in thousands):



	Year Ended December 31,
	2016			2015			2014

Domestic	$	(61,484	)	$	(485,760	)	$	73,700
Foreign	(32,431		)	7,590			188,821
	$	(93,915	)	$	(478,170	)	$	262,521

Schedule of differences between the U.S. statutory rate and effective rate from continuing operations

The primary differences between the U.S. statutory rate and our effective rate are as follows:



	Year Ended December 31,
	2016		2015		2014

Statutory rate	35.0	%	35.0	%	35.0	%
Foreign provision	(5.1	)	(13.7	)	(9.1	)
Goodwill impairment	(16.8	)	—		—
Other	0.2		(0.1	)	(0.4	)
Effective rate	13.3	%	21.2	%	25.5	%

Schedule of deferred income taxes



	December 31,
	2016			2015
Deferred tax liabilities:
Depreciation	$	192,777		$	173,863
Original issuance discount on 2022 Notes and 2032 Notes	11,802			17,957
Equity investments in production facilities	—			8,029
Prepaid and other	1,448			1,883
Total deferred tax liabilities	$	206,027		$	201,732
Deferred tax assets:
Net operating losses	$	(20,910	)	$	(23,595	)
Reserves, accrued liabilities and other	(38,131		)	(52,672		)
Total deferred tax assets	(59,041		)	(76,267		)
Valuation allowance	3,771			1,936
Net deferred tax liabilities	$	150,757		$	127,401
Deferred income tax is presented as:
Current deferred tax assets	$	(16,594	)	$	(53,573	)
Non-current deferred tax liabilities	167,351			180,974
Net deferred tax liabilities	$	150,757		$	127,401

Reconciliation of beginning and ending amount of unrecognized tax benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2016, 2015 and 2014 is as follows (in thousands):



	2016		2015		2014

Balance at January 1,	$	—	$	—	$	4,723
Additions for tax positions of prior years	343		—		—
Reductions for tax positions of prior years	—		—		(4,723		)
Balance at December 31,	$	343	$	—	$	—

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders' Equity Note [Abstract]

Components of Accumulated OCI

The components of Accumulated OCI are as follows (in thousands):



	December 31,
	2016			2015

Cumulative foreign currency translation adjustment	$	(78,953	)	$	(43,010	)
Unrealized loss on hedges, net ⁽¹⁾	(18,021		)	(27,891		)
Accumulated other comprehensive loss	$	(96,974	)	$	(70,901	)


(1)	Amounts relate to foreign currency hedges for the Grand Canyon, the Grand Canyon II and the Grand Canyon III charters as well as interest rate swap contracts for the Term Loan and the Nordea Q5000 Loan, and are net of deferred income taxes totaling $9.7 million and $15.1 million as of December 31, 2016 and 2015, respectively (Note 18).

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Computations of basic and diluted EPS



	Year Ended December 31,
	2016				2015				2014
	Income			Shares	Income			Shares	Income			Shares
Basic:
Net income (loss) applicable to common shareholders	$	(81,445	)		$	(376,980	)		$	195,047
Less: Undistributed earnings allocated to participating securities	—				—				(1,018		)
Undistributed earnings (loss) allocated to common shares	$	(81,445	)	111,612	$	(376,980	)	105,416	$	194,029		105,029



Diluted:
Undistributed earnings (loss) allocated to common shares	$	(81,445	)	111,612	$	(376,980	)	105,416	$	194,029	105,029
Effect of dilutive securities:
Share-based awards other than participating securities	—			—	—			—	—		16
Undistributed earnings reallocated to participating securities	—			—	—			—	—		—
Net income (loss) applicable to common shareholders	$	(81,445	)	111,612	$	(376,980	)	105,416	$	194,029	105,045

Schedule of shares excluded from the diluted per share calculations

Shares that otherwise would have been included in the diluted per share calculations assuming we had earnings are as follows (in thousands):



	Year Ended December 31,
	2016	2015

Diluted shares (as reported)	111,612	105,416
Share-based awards	440	59
Total	112,052	105,475



	Year Ended December 31,
	2016	2015	2014

2022 Notes	1,475	—	—
2032 Notes	6,891	7,995	7,995

Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of share-based awards

The following grants of share-based awards were made in 2016 under the 2005 Incentive Plan:



Date of Grant	Shares	Grant Date Fair Value Per Share		Vesting Period

January 4, 2016 ⁽¹⁾	1,143,062	$	5.26	33% per year over three years
January 4, 2016 ⁽²⁾	1,143,062	$	7.13	100% on January 1, 2019
January 4, 2016 ⁽³⁾	11,763	$	5.26	100% on January 1, 2018
February 1, 2016 ⁽¹⁾	18,610	$	4.03	33% per year over three years
February 1, 2016 ⁽²⁾	18,610	$	7.13	100% on January 1, 2019
April 1, 2016 ⁽³⁾	13,727	$	5.60	100% on January 1, 2018
July 1, 2016 ⁽³⁾	8,476	$	6.76	100% on January 1, 2018
October 3, 2016 ⁽³⁾	7,803	$	8.13	100% on January 1, 2018
December 2, 2016 ⁽⁴⁾	94,680	$	11.09	33% per year over three years


(1)	Reflects the grant of restricted stock to our executive officers and select management employees.


(2)	Reflects the grant of PSUs to our executive officers and select management employees.


(3)	Reflects the grant of restricted stock to certain independent members of our Board of Directors who have made an election to take their quarterly fees in stock in lieu of cash.


(4)	Reflects annual equity grants to each independent member of our Board of Directors.

Summary of information about restricted stock

The following table summarizes information about our restricted stock:



	Year Ended December 31,
	2016				2015				2014
	Shares		Grant Date Fair Value ⁽¹⁾		Shares		Grant Date Fair Value ⁽¹⁾		Shares		Grant Date Fair Value ⁽¹⁾

Awards outstanding at beginning of year	661,124		$	16.28	554,960		$	17.54	771,942		$	13.62
Granted	1,298,121		5.70		501,076		15.57		139,455		23.22
Vested ^{(2) (3)}	(305,588	)	16.94		(332,223	)	16.44		(356,437	)	11.27
Forfeited	(75,684	)	7.76		(62,689	)	20.93		—		—
Awards outstanding at end of year ⁽³⁾	1,577,973		$	7.86	661,124		$	16.28	554,960		$	17.54


(1)	Represents the weighted average grant date fair value, which is based on the quoted closing market price of our common stock on the trading day prior to the date of grant.


(2)	Total fair value of restricted stock and RSUs that vested during the years ended December 31, 2016, 2015 and 2014 was $2.2 million, $5.1 million and $8.2 million, respectively.


(3)	The vested and year-end amounts in 2014 each included 33,760 shares of RSUs with the grant date fair value of 15.80 per share. We paid $0.7 million in cash upon vesting of these RSUs in January 2015.

Business Segment Information (Tables)

12 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Schedule of financial data by reportable segment

Certain financial data by reportable segment are summarized as follows (in thousands):



	Year Ended December 31,
	2016			2015			2014
Net revenues —
Well Intervention	$	294,000		$	373,301		$	667,849
Robotics	160,580			301,026			420,224
Production Facilities	72,358			75,948			93,175
Other	—			—			358
Intercompany elimination	(39,356		)	(54,473		)	(74,450		)
Total	$	487,582		$	695,802		$	1,107,156



Income (loss) from operations —
Well Intervention ⁽¹⁾	$	14,910		$	(194,381	)	$	204,810
Robotics ⁽²⁾	(72,250		)	27,832			68,329
Production Facilities ⁽³⁾	33,861			(106,847		)	41,138
Corporate and other ⁽⁴⁾	(39,384		)	(33,866		)	(51,600		)
Intercompany elimination	(372		)	(98		)	(921		)
Total	$	(63,235	)	$	(307,360	)	$	261,756



	Year Ended December 31,
	2016			2015			2014
Net interest expense —
Well Intervention	$	(109	)	$	(102	)	$	(252	)
Robotics	(25		)	29			(5		)
Production Facilities	—			385			384
Corporate and elimination	31,373			26,602			17,732
Total	$	31,239		$	26,914		$	17,859



Equity in earnings (losses) of investments	$	(2,166	)	$	(124,345	)	$	879



Income (loss) before income taxes —
Well Intervention ⁽¹⁾	$	18,813		$	(193,572	)	$	211,725
Robotics ^{(2) (5)}	(73,533		)	2,454			61,025
Production Facilities ⁽³⁾	31,695			(231,577		)	41,633
Corporate and other and eliminations ^{(4) (6)}	(70,890		)	(55,475		)	(51,862		)
Total	$	(93,915	)	$	(478,170	)	$	262,521



Income tax provision (benefit) —
Well Intervention	$	12,531		$	(1,230	)	$	50,102
Robotics	(9,948		)	515			21,612
Production Facilities	11,093			(81,052		)	14,395
Corporate and other and eliminations	(26,146		)	(19,423		)	(19,138		)
Total	$	(12,470	)	$	(101,190	)	$	66,971



Capital expenditures —
Well Intervention	$	185,892		$	307,879		$	283,635
Robotics	720			10,700			51,348
Production Facilities	74			1,867			869
Corporate and other	(199		)	(135		)	1,060
Total	$	186,487		$	320,311		$	336,912



Depreciation and amortization —
Well Intervention	$	68,392	$	66,095	$	57,570
Robotics	25,848		26,724		24,478
Production Facilities	13,952		21,340		21,278
Corporate and eliminations	5,995		6,242		6,019
Total	$	114,187	$	120,401	$	109,345


(1)	Amount in 2016 included a $1.3 million gain on the sale of the Helix 534 in December 2016. Amount in 2015 included impairment charges of $205.2 million for the Helix 534 and $6.3 million for certain capitalized vessel project costs and a $16.4 million goodwill impairment charge related to our U.K. well intervention reporting unit.


(2)	Amount in 2016 included a $45.1 million goodwill impairment charge related to our robotics reporting unit.


(3)	Amount in 2015 included a $133.4 million impairment charge for the HP I.


(4)	Amount in 2014 included a $10.5 million gain on the sale of our Ingleside spoolbase in January 2014.


(5)	Amount in 2015 included unrealized losses totaling $18.3 million on our foreign currency exchange contracts associated with the Grand Canyon, Grand Canyon II and Grand Canyon III chartered vessels.


(6)	Amount in 2014 included $16.9 million of income with $7.2 million from an insurance reimbursement related to asset retirement work previously performed and the remaining from our overriding royalty income.

Summary of intercompany segment revenues

Intercompany segment revenues are as follows (in thousands):



	Year Ended December 31,
	2016		2015		2014

Well Intervention	$	8,442	$	22,855	$	29,875
Robotics	30,914		31,618		44,575
Total	$	39,356	$	54,473	$	74,450

Schedule of revenue by individually significant region

Revenues by individually significant region are as follows (in thousands):



	Year Ended December 31,
	2016		2015		2014

United States	$	298,279	$	298,391	$	403,994
North Sea ⁽¹⁾	137,313		263,438		504,016
Other	51,990		133,973		199,146
Total	$	487,582	$	695,802	$	1,107,156


(1)	Includes revenues of $123.6 million, $187.7 million and $362.7 million, respectively, which were from the U.K.

Schedule of property and equipment, net of accumulated depreciation, by individually significant region

The following table provides our property and equipment, net of accumulated depreciation, by individually significant geographic location of our assets (in thousands):



	December 31,
	2016		2015

United States	$	956,458	$	1,024,691
United Kingdom	299,699		352,740
Singapore ⁽¹⁾	194,649		112,313
Other	200,804		113,265
Total	$	1,651,610	$	1,603,009


(1)	Primarily includes the Q7000 vessel under construction.

Schedule of total assets by reportable segment

The following table reflects total assets by reportable segment (in thousands):



	December 31,
	2016		2015

Well Intervention	$	1,596,517	$	1,484,109
Robotics	186,901		274,926
Production Facilities	158,192		182,007
Corporate and other	305,331		458,917
Total	$	2,246,941	$	2,399,959

Commitments And Contingencies And Other Matters (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Schedule of future minimum rental payments

Future minimum rentals at December 31, 2016 are as follows (in thousands):



	Vessels		Facilities and Other		Total

2017	$	156,446	$	5,788	$	162,234
2018	142,407		5,163		147,570
2019	131,665		5,123		136,788
2020	111,650		4,753		116,403
2021	99,563		4,667		104,230
Thereafter	149,861		19,566		169,427
Total lease commitments	$	791,592	$	45,060	$	836,652

Statement Of Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2016

Supplemental Cash Flow Information [Abstract]

Schedule of supplemental cash flow information

The following table provides supplemental cash flow information (in thousands):



	Year Ended December 31,
	2016		2015		2014

Interest paid, net of interest capitalized	$	18,749	$	14,555	$	11,628
Income taxes paid	5,635		16,905		70,509

Allowance Accounts (Tables)

12 Months Ended

Dec. 31, 2016

Valuation and Qualifying Accounts [Abstract]

Summary of activity in valuation accounts

The following table sets forth the activity in our valuation accounts for each of the three years in the period ended December 31, 2016 (in thousands):



	Allowance for Uncollectible Accounts			Deferred Tax Asset Valuation Allowance

Balance at December 31, 2013	$	2,234		$	22,860
Additions ⁽¹⁾	5,331			—
Deductions ⁽²⁾	(2,830		)	—
Adjustments	—			216
Balance at December 31, 2014	4,735			23,076
Additions ⁽¹⁾	3,275			—
Deductions ⁽²⁾	(7,660		)	—
Adjustments ⁽³⁾	—			(21,140		)
Balance at December 31, 2015	350			1,936
Additions ⁽¹⁾	1,778			—
Deductions ⁽²⁾	(350		)	—
Adjustments ⁽⁴⁾	—			1,835
Balance at December 31, 2016	$	1,778		$	3,771


(1)	The increase in allowance for uncollectible accounts primarily reflects charges associated with the provision for uncertain collection of a portion of our existing trade receivables related to our Robotics segment.


(2)	The decrease in allowance for uncollectible accounts reflects the write-offs of trade receivables that are either settled or deemed uncollectible.


(3)	The decrease in valuation allowance primarily reflects a $20.6 million reduction related to the loss of deferred tax assets for net operating losses within our Australian subsidiaries.


(4)	The increase in valuation allowance primarily reflects additional net operating losses in Brazil for which insufficient future taxable income exists to offset the losses.

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of other financial instruments measured at fair value on a recurring basis

The following tables provide additional information relating to other financial instruments measured at fair value on a recurring basis (in thousands):



	Fair Value Measurements at December 31, 2016 Using								Valuation Approach
	Level 1		Level 2 ⁽¹⁾		Level 3		Total		Valuation Approach
Assets:
Interest rate swaps	$	—	$	451	$	—	$	451	(c)

Liabilities:
Foreign exchange contracts	—		38,170		—		38,170		(c)
Interest rate swaps	—		751		—		751		(c)
Total net liability	$	—	$	38,470	$	—	$	38,470



	Fair Value Measurements at December 31, 2015 Using								Valuation Approach
	Level 1		Level 2 ⁽¹⁾		Level 3		Total		Valuation Approach
Assets:
Interest rate swaps	$	—	$	413	$	—	$	413	(c)

Liabilities:
Foreign exchange contracts	—		61,427		—		61,427		(c)
Interest rate swaps	—		1,473		—		1,473		(c)
Total net liability	$	—	$	62,487	$	—	$	62,487

(1)

Schedule of carrying values and estimated fair values of long-term debt

The carrying values and estimated fair values of our long-term debt are as follows (in thousands):



	December 31,
	2016				2015
	Carrying Value ⁽¹⁾		Fair Value ⁽²⁾		Carrying Value ⁽¹⁾		Fair Value ⁽²⁾

Term Loan (matures June 2018)	$	192,258	$	192,258	$	255,000	$	248,467
Nordea Q5000 Loan (matures April 2020)	196,429		192,746		232,143		221,553
MARAD Debt (matures February 2027)	83,222		92,049		89,148		104,897
2022 Notes (mature May 2022)	125,000		130,156		—		—
2032 Notes (mature March 2032)	60,115		59,965		200,000		150,250
Total debt	$	657,024	$	667,174	$	776,291	$	725,167


(1)	Carrying value includes current maturities and excludes the related unamortized debt discount and debt issuance costs. See Note 7 for additional disclosures on our long-term debt.

(2)

Derivative Instruments And Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of balance sheet location and fair value of derivative instruments designated as hedging instruments

The following table presents the balance sheet location and fair value of our derivative instruments that were designated as hedging instruments (in thousands):



	December 31,
	2016			2015
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Asset Derivative Instruments:
Interest rate swaps	Other assets, net	$	451	Other assets, net	$	413
		$	451		$	413

Liability Derivative Instruments:
Foreign exchange contracts	Accrued liabilities	$	14,056	Accrued liabilities	$	14,955
Interest rate swaps	Accrued liabilities	751		Accrued liabilities	1,473
Foreign exchange contracts	Other non-current liabilities	13,383		Other non-current liabilities	28,458
		$	28,190		$	44,886

Schedule of balance sheet location and fair value of derivative instruments not designated as hedging instruments

The following table presents the balance sheet location and fair value of our derivative instruments that were not designated as hedging instruments (in thousands):



	December 31,
	2016			2015
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Liability Derivative Instruments:
Foreign exchange contracts	Accrued liabilities	$	3,923	Accrued liabilities	$	6,763
Foreign exchange contracts	Other non-current liabilities	6,808		Other non-current liabilities	11,251
		$	10,731		$	18,014

Schedule of impact of derivative instruments designated as hedging instruments on Accumulated OCI



	Gain (Loss) Recognized in OCI on Derivative Instruments, Net of Tax (Effective Portion)
	Year Ended December 31,
	2016		2015			2014

Foreign exchange contracts	$	9,397	$	4,734		$	(22,170	)
Interest rate swaps	473		(534		)	70
	$	9,870	$	4,200		$	(22,100	)

Schedule of loss reclassified from Accumulated OCI into earnings



	Location of Loss Reclassified from Accumulated OCI into Earnings	Loss Reclassified from Accumulated OCI into Earnings (Effective Portion)
		Year Ended December 31,
		2016			2015			2014

Foreign exchange contracts	Cost of sales	$	(10,827	)	$	(11,516	)	$	(2,507	)
Interest rate swaps	Net interest expense	(2,024		)	(2,143		)	(858		)
		$	(12,851	)	$	(13,659	)	$	(3,365	)

Schedule of impact of derivative instruments not designated as hedging instruments on consolidated statement of operations

The following table presents the impact that derivative instruments not designated as hedging instruments had on our consolidated statements of operations (in thousands):



	Location of Gain (Loss) Recognized in Earnings on Derivative Instruments	Gain (Loss) Recognized in Earnings on Derivative Instruments
		Year Ended December 31,
		2016		2015			2014

Foreign exchange contracts	Other income (expense), net	$	1,198	$	(18,014	)	$	7
		$	1,198	$	(18,014	)	$	7

Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Summary of consolidated quarterly financial information

The following is a summary of consolidated quarterly financial information (in thousands, except per share amounts):



	Quarter Ended
	March 31,			June 30,			September 30,		December 31,
2016
Net revenues	$	91,039		$	107,267		$	161,245	$	128,031
Gross profit (loss)	(16,930		)	5,658			40,184		17,604
Net income (loss) applicable to common shareholders ⁽¹⁾	(27,823		)	(10,671		)	11,462		(54,413		)
Basic earnings (loss) per common share	$	(0.26	)	$	(0.10	)	$	0.10	$	(0.46	)
Diluted earnings (loss) per common share	$	(0.26	)	$	(0.10	)	$	0.10	$	(0.46	)



	Quarter Ended
	March 31,		June 30,			September 30,		December 31,
2015
Net revenues	$	189,641	$	166,016		$	182,462	$	157,683
Gross profit (loss) ⁽²⁾	34,947		24,208			31,969		(324,898		)
Net income (loss) applicable to common shareholders ⁽³⁾	19,642		(2,635		)	9,880		(403,867		)
Basic earnings (loss) per common share	$	0.19	$	(0.03	)	$	0.09	$	(3.83	)
Diluted earnings (loss) per common share	$	0.19	$	(0.03	)	$	0.09	$	(3.83	)


(1)	Amount in the fourth quarter of 2016 included a $45.1 million goodwill impairment charge related to our robotics reporting unit (Notes 2 and 6).


(2)	Amount in the fourth quarter of 2015 included impairment charges of $205.2 million for the Helix 534 and $133.4 million for the HP I and $6.3 million for certain capitalized vessel project costs (Note 4).

(3)

Organization (Details) $ in Thousands	1 Months Ended		12 Months Ended
Organization (Details) $ in Thousands	Feb. 29, 2016 USD ($)	Feb. 28, 2014 vessel	Dec. 31, 2016 USD ($) segment vessel	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments \| segment			3
Sale of ownership interest for cash \| $			$ 25,000	$ 0	$ 0
Deepwater Gateway, L.L.C. [Member]
Segment Reporting Information [Line Items]
Sale of ownership interest for cash \| $	$ 25,000
Robotics [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels			3
Q5000 [Member]
Segment Reporting Information [Line Items]
Term of contract			5 years
Monohull Vessels [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels		2
Monohull Vessels [Member] \| Well Intervention [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels			2

Summary Of Significant Accounting Policies - Principles Of Consolidation (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Noncontrolling interest, ownership percentage by noncontrolling owners	19.00%
Acquisition of noncontrolling interests	$ 20,100	$ 0	$ 0	$ 20,085

Summary Of Significant Accounting Policies - Property And Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Repair and maintenance expense	$ 25.5	$ 32.8	$ 44.6

Summary Of Significant Accounting Policies - Goodwill (Details) $ in Thousands		3 Months Ended		12 Months Ended
	Nov. 01, 2016 segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Goodwill [Line Items]
Number of reporting unit \| segment	1
Goodwill impairment charge				$ 45,107	$ 16,399	$ 0
Robotics [Member]
Goodwill [Line Items]
Goodwill impairment charge		$ 45,100		45,107	0
Well Intervention [Member]
Goodwill [Line Items]
Goodwill impairment charge			$ 16,400	$ 0	16,399
Well Intervention [Member] \| United Kingdom [Member]
Goodwill [Line Items]
Goodwill impairment charge					$ 16,400

Summary Of Significant Accounting Policies - Recertification Costs And Deferred Dry Dock Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Deferred dry dock costs, net (Note 2)	$ 14,766	$ 19,615
Accumulated amortization deferred dry dock	10,700	18,300
Dry dock amortization expense	$ 14,000	$ 10,800	$ 14,100
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Dry dock amortization period	30 months
Dry dock recertification process period	1 month
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Dry dock amortization period	60 months
Dry dock recertification process period	2 months

Summary Of Significant Accounting Policies - Foreign Currency (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Foreign currency translation losses included in Accumulated OCI	$ 35,943	$ 12,849	$ 19,464
Foreign currency transaction gains (losses)	$ 200	$ (1,200)	$ 2,500

Summary Of Significant Accounting Policies - Major Customers And Concentration Of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
BP [Member]
Revenue, Major Customer [Line Items]
Percentage of concentration risk	17.00%
Shell [Member]
Revenue, Major Customer [Line Items]
Percentage of concentration risk	11.00%	16.00%
Talos [Member]
Revenue, Major Customer [Line Items]
Percentage of concentration risk		11.00%
Anadarko [Member]
Revenue, Major Customer [Line Items]
Percentage of concentration risk			13.00%

Summary Of Significant Accounting Policies - Asset Retirement Obligations (Details) $ in Millions	12 Months Ended
	Dec. 31, 2014 USD ($)
Accounting Policies [Abstract]
Proceeds from insurance reimbursement	$ 7.2

Summary Of Significant Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unamortized debt issuance costs	$ 11,963	$ 11,993
Accounting Standards Update 2015-03 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unamortized debt issuance costs		$ 12,000

Details Of Certain Accounts - Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Note receivable (Note 4)	$ 10,000	$ 10,000
Prepaid insurance	4,426	5,433
Other prepaids	9,547	10,142
Deferred costs	7,971	609
Spare parts inventory	2,548	4,985
Income tax receivable	880	0
Value added tax receivable	1,345	7,842
Other	671	507
Total other current assets	$ 37,388	$ 39,518

Details Of Certain Accounts - Other Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Note receivable, net	$ 2,827	$ 0
Prepaids	6,418	0
Deferred dry dock costs, net (Note 2)	14,766	19,615
Deferred costs	30,738	0
Deferred financing costs, net	3,745	7,863
Charter fee deposit (Note 14)	12,544	12,544
Other	1,511	1,586
Total other assets, net	72,549	$ 41,608
Allowance for note receivable	$ 4,200
Noncurrent note receivable, interest rate (as a percent)	3.00%

Details Of Certain Accounts - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued payroll and related benefits	$ 20,705	$ 14,775
Deferred revenue	8,911	12,841
Accrued interest	3,758	4,854
Derivative liability (Note 18)	18,730	23,192
Taxes payable excluding income tax payable	1,214	8,136
Other	5,296	7,843
Total accrued liabilities	$ 58,614	$ 71,641

- Definition

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

+ References + Details

Details Of Certain Accounts - Other Non-Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Investee losses in excess of investment (Note 5)	$ 10,238	$ 8,308
Deferred gain on sale of property (Note 4)	5,761	0
Deferred revenue	8,598	0
Derivative liability (Note 18)	20,191	39,709
Other	8,197	3,398
Total other non-current liabilities	$ 52,985	$ 51,415

- Definition

The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References + Details

Property And Equipment - Gross Components Of Property And Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment	$ 2,450,890	$ 2,544,857
Vessels [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 1,860,379	1,944,753
Vessels [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Vessels [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
ROVs, trenchers and ROVDrills [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 309,603	311,971
Estimated useful life	10 years
Machinery, equipment, buildings and leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 280,908	$ 288,133
Machinery, equipment, buildings and leasehold improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Machinery, equipment, buildings and leasehold improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years

Property And Equipment - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended					3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2015	Dec. 31, 2014	Jan. 31, 2014	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Proceeds from sale of assets							$ 13,177	$ 17,592	$ 13,574
Note receivable, remaining principal balance	$ 10,000	$ 10,000				$ 10,000	10,000	10,000
Asset impairment charges							0	345,010	0
Gain on disposition of assets, net							$ 1,290	92	$ 10,240
Spoolbase Facility [Member]
Property, Plant and Equipment [Line Items]
Sales price of property and equipment					$ 45,000
Proceeds from sale of assets					15,000
Note receivable					$ 30,000
Note receivable, interest rate	6.00%						6.00%
Note receivable, periodic principal payment		10,000	$ 7,500	$ 2,500
Note receivable, remaining principal balance	$ 10,000						$ 10,000
Helix 534 [Member]
Property, Plant and Equipment [Line Items]
Sales price of property and equipment	2,800
Asset impairment charges						205,200		205,200
Estimated fair value		1,000				1,000		1,000
Write off of deferred dry dock costs		9,000				9,000		9,000
Unrecorded gain contingency	$ 400						400
Gain on disposition of assets, net							$ 1,300
HP I [Member]
Property, Plant and Equipment [Line Items]
Asset impairment charges						133,400		133,400
Estimated fair value		$ 124,300				124,300		124,300
Capitalized Vessel Project Costs [Member]
Property, Plant and Equipment [Line Items]
Impairment charges to write off capitalized costs						$ 6,300		$ 6,300

Property And Equipment - Sale Leaseback Transaction (Details) - Scotland [Member] $ in Millions	1 Months Ended
	Jan. 31, 2016 USD ($) renewal_option
Sale Leaseback Transaction [Line Items]
Proceeds from sale leaseback transaction	$ 11.0
Term of lease agreement	15 years
Number of renewal options \| renewal_option	2
Term of renewal option	5 years
Deferred gain from sale leaseback transaction	$ 7.6

Equity Investments - Narrative (Details)	1 Months Ended				12 Months Ended
Equity Investments - Narrative (Details)	Feb. 29, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jul. 31, 2015 USD ($)	Dec. 31, 2004 USD ($)	Dec. 31, 2016 USD ($) ft	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Equity Method Investments [Line Items]
Consideration transferred for business sold			$ 1,500,000,000
Investee losses in excess of investment		$ 8,308,000			$ 10,238,000	$ 8,308,000
Loss from equity method investments					2,166,000	124,345,000	$ (879,000)
Equity method investment		$ 26,200,000			0	26,200,000
Sale of ownership interest for cash					$ 25,000,000	$ 0	$ 0
Independence Hub, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest		20.00%				20.00%
Water depth (in feet) \| ft					8,000
Impairment charge		$ 343,300,000
Estimated fair value		0				$ 0
Asset retirement obligation		42,100,000			$ 52,500,000	42,100,000
Investee losses in excess of investment		8,300,000			10,200,000	8,300,000
Loss from equity method investments					$ 2,200,000	74,900,000
Capitalized interest		$ 3,600,000				$ 3,600,000
Participation fee				$ 1,000,000
Deepwater Gateway, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest		50.00%				50.00%
Impairment charge		$ 96,700,000
Estimated fair value		70,800,000				$ 70,800,000
Asset retirement obligation		20,800,000				20,800,000
Loss from equity method investments						49,400,000
Capitalized interest		1,200,000				1,200,000
Equity method investment		$ 26,200,000				$ 26,200,000
Cash distribution	$ 1,200,000
Sale of ownership interest for cash	$ 25,000,000

Equity Investments - Distributions From Equity Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 1,200	$ 7,000	$ 8,790
Deepwater Gateway, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	1,200	5,200	6,150
Independence Hub, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 0	$ 1,800	$ 2,640

Equity Investments - Summary Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues	$ 14,791	$ 23,284
Operating income (loss)	(448,138)	411
Net income (loss)	(448,138)	$ 411
Equity Method Investment, Summarized Financial Information, Balance Sheet [Abstract]
Current assets	3,181
Noncurrent assets	70,812
Current liabilities	180
Noncurrent liabilities	$ 62,951

Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Balance at beginning of period			$ 45,107	$ 62,146
Impairment loss			(45,107)	(16,399)	$ 0
Other adjustments				(640)
Balance at end of period	$ 0	$ 45,107	0	45,107	62,146
Well Intervention [Member]
Goodwill [Roll Forward]
Balance at beginning of period			0	17,039
Impairment loss		(16,400)	0	(16,399)
Other adjustments				(640)
Balance at end of period	0	0	0	0	17,039
Robotics [Member]
Goodwill [Roll Forward]
Balance at beginning of period			45,107	45,107
Impairment loss	(45,100)		(45,107)	0
Other adjustments				0
Balance at end of period	$ 0	$ 45,107	$ 0	$ 45,107	$ 45,107

Long-Term Debt - Schedule Of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Nov. 01, 2016	Dec. 31, 2015	Mar. 31, 2012
Debt Instrument [Line Items]
Carrying value	$ 657,024
Unamortized debt discounts	(19,094)
Unamortized debt issuance costs	(11,963)		$ (11,993)
Total debt	625,967		749,335
Less current maturities	(67,571)		(71,640)
Long-term debt	558,396		677,695
Term Loan Maturing June 2018 [Member]
Debt Instrument [Line Items]
Carrying value	192,258		255,000
Unamortized debt discounts	0
Unamortized debt issuance costs	(1,391)
Less current maturities	(25,634)
Long-term debt	165,233
Convertible Senior Notes Maturing May 2022 [Member]
Debt Instrument [Line Items]
Carrying value	125,000	$ 125,000	0
Unamortized debt discounts	(16,513)	$ (16,900)
Unamortized debt issuance costs	(2,790)
Less current maturities	0
Long-term debt	105,697
Convertible Senior Notes Maturing March 2032 [Member]
Debt Instrument [Line Items]
Carrying value	60,115		200,000	$ 200,000
Unamortized debt discounts	(2,581)		(14,963)	$ (35,400)
Unamortized debt issuance costs	(231)
Less current maturities	0
Long-term debt	57,303
MARAD Debt Maturing February 2027 [Member]
Debt Instrument [Line Items]
Carrying value	83,222		89,148
Unamortized debt discounts	0
Unamortized debt issuance costs	(5,001)
Less current maturities	(6,222)
Long-term debt	71,999
Nordea Q5000 Loan Maturing April 2020 [Member]
Debt Instrument [Line Items]
Carrying value	196,429		$ 232,143
Unamortized debt discounts	0
Unamortized debt issuance costs	(2,550)
Less current maturities	(35,715)
Long-term debt	$ 158,164

Long-Term Debt - Credit Agreement (Details)	1 Months Ended				12 Months Ended
Long-Term Debt - Credit Agreement (Details)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Feb. 29, 2016 USD ($)	Jun. 30, 2013 USD ($)	Dec. 31, 2016 USD ($) foreign_subsidiary	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2013 USD ($)
Debt Instrument [Line Items]
Amortization of debt issuance costs					$ 7,733,000	$ 5,664,000	$ 4,870,000
Number of foreign subsidiaries designated as not subject to Credit Agreement covenants \| foreign_subsidiary					5
Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Notional amount								$ 148,100,000
Term Loan Maturing June 2018 [Member]
Debt Instrument [Line Items]
Borrowing capacity				$ 300,000,000
Scheduled principal installments					$ 25,600,000
Balloon payment	$ 160,200,000				$ 160,200,000
Prepayment of debt	25,000,000	$ 8,000,000
Maturity date				Jun. 19, 2018
Term Loan Maturing June 2018 [Member] \| Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Notional amount								$ 148,100,000
Fixed LIBOR rate on interest rate swaps (as a percent)								0.75%
Term Loan Maturing June 2018 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					4.50%
Term Loan Maturing June 2018 [Member] \| Minimum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					1.00%
Term Loan Maturing June 2018 [Member] \| Minimum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					2.00%
Term Loan Maturing June 2018 [Member] \| Maximum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					3.00%
Term Loan Maturing June 2018 [Member] \| Maximum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					4.00%
Revolving Credit Facility Maturing June 2018 [Member]
Debt Instrument [Line Items]
Borrowing capacity			$ 400,000,000	$ 600,000,000
Increase in aggregate commitments (up to)				$ 200,000,000
Available borrowing capacity	18,900,000				$ 18,900,000
Letters of credit issued	$ 4,100,000				$ 4,100,000
Commitment fee percentage					0.50%
Amortization of debt issuance costs			$ 2,500,000

Long-Term Debt - Schedule Of Consolidated Interest Coverage Ratio (Details) - Line of Credit [Member] - February 2016 Amendment [Member]	Feb. 29, 2016
December 31, 2016 through and including March 31, 2017 [Member]
Debt Instrument [Line Items]
Minimum Consolidated Interest Coverage Ratio	2.75
June 30, 2017 and each fiscal quarter thereafter [Member]
Debt Instrument [Line Items]
Minimum Consolidated Interest Coverage Ratio	3

Long-Term Debt - Schedule Of Consolidated Leverage Ratio (Details) - Line of Credit [Member] - February 2016 Amendment [Member]	Feb. 29, 2016
December 31, 2016 [Member]
Debt Instrument [Line Items]
Maximum Consolidated Leverage Ratio	5
March 31, 2017 [Member]
Debt Instrument [Line Items]
Maximum Consolidated Leverage Ratio	4.75
June 30, 2017 [Member]
Debt Instrument [Line Items]
Maximum Consolidated Leverage Ratio	4.25
September 30, 2017 [Member]
Debt Instrument [Line Items]
Maximum Consolidated Leverage Ratio	3.75
December 31, 2017 and each fiscal quarter thereafter [Member]
Debt Instrument [Line Items]
Maximum Consolidated Leverage Ratio	3.5

Long-Term Debt - Schedule Of Consolidated Leverage Ratio Cash Balances (Details) - USD ($)	Dec. 31, 2016	Feb. 29, 2016
Debt Instrument [Line Items]
Minimum Cash Balance	$ 150,000,000
Greater than or equal to 4.50x [Member] \| Line of Credit [Member] \| February 2016 Amendment [Member]
Debt Instrument [Line Items]
Minimum Cash Balance		$ 150,000,000.00
Greater than or equal to 4.00x but less than 4.50x [Member] \| Line of Credit [Member] \| February 2016 Amendment [Member]
Debt Instrument [Line Items]
Minimum Cash Balance		100,000,000.00
Greater than or equal to 3.50x but less than 4.00x [Member] \| Line of Credit [Member] \| February 2016 Amendment [Member]
Debt Instrument [Line Items]
Minimum Cash Balance		50,000,000.00
Less than 3.50x [Member] \| Line of Credit [Member] \| February 2016 Amendment [Member]
Debt Instrument [Line Items]
Minimum Cash Balance		$ 0.00

Long-Term Debt - Convertible Senior Notes Due 2022 (Details) $ / shares in Units, $ in Thousands		1 Months Ended
	Nov. 01, 2016 USD ($) $ / shares	Mar. 31, 2012 USD ($) $ / shares	Dec. 31, 2016 USD ($)	Jul. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Principal amount			$ 657,024
Unamortized debt discount			19,094
Convertible Senior Notes Maturing May 2022 [Member]
Debt Instrument [Line Items]
Principal amount	$ 125,000		125,000			$ 0
Net proceeds from debt issuance	$ 121,700
Interest rate (as a percent)	4.25%
Frequency of periodic payment	semi-annually
Maturity date	May 01, 2022
Initial conversion ratio	0.0719748
Initial conversion price per share (in dollars per share) \| $ / shares	$ 13.89
Redemption price as a percentage of principal amount	100.00%
Minimum percentage in aggregate principal amount	25.00%
Unamortized debt discount	$ 16,900		16,513
Expected life used to estimate fair value	5 years 6 months
Effective interest rate (as a percent)	7.30%
Carrying amount of equity component	$ 11,000
Convertible Senior Notes Maturing March 2032 [Member]
Debt Instrument [Line Items]
Principal amount		$ 200,000	60,115			200,000
Repurchased principal amount	$ 125,000			$ 7,600	$ 7,300
Interest rate (as a percent)		3.25%
Frequency of periodic payment		semi-annually
Maturity date		Mar. 15, 2032
Initial conversion ratio		0.0399752
Initial conversion price per share (in dollars per share) \| $ / shares		$ 25.02
Redemption price as a percentage of principal amount		100.00%
Unamortized debt discount		$ 35,400	$ 2,581			$ 14,963
Expected life used to estimate fair value		6 years
Effective interest rate (as a percent)		6.90%
Carrying amount of equity component		$ 22,500

Long-Term Debt - Convertible Senior Notes Dues 2032 (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Nov. 30, 2016	Jul. 31, 2016	Mar. 31, 2012	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 01, 2016	Jun. 30, 2016
Debt Instrument [Line Items]
Principal amount				$ 657,024
Unamortized debt discount				19,094
Loss on repurchase of long-term debt				(3,540)	$ 0	$ 0
Convertible Senior Notes Maturing March 2032 [Member]
Debt Instrument [Line Items]
Principal amount			$ 200,000	60,115	200,000
Interest rate (as a percent)			3.25%
Frequency of periodic payment			semi-annually
Maturity date			Mar. 15, 2032
Initial conversion ratio			0.0399752
Initial conversion price per share (in dollars per share)			$ 25.02
Redemption price as a percentage of principal amount			100.00%
Repurchase price as a percentage of principal amount			100.00%
Expected life used to estimate fair value			6 years
Effective interest rate (as a percent)			6.90%
Carrying amount of equity component			$ 22,500
Unamortized debt discount			$ 35,400	2,581	$ 14,963
Repurchased principal amount		$ 7,600					$ 125,000	$ 7,300
Repurchase amount		7,000						$ 6,500
Accrued interest included in repurchase amount	$ 500	$ 100
Loss on repurchase of long-term debt				(3,500)
Amortization of debt issuance costs and discounts				7,500
Re-acquisition of equity component				$ 2,500

Long-Term Debt - MARAD Debt (Details) - MARAD Debt Maturing February 2027 [Member]	1 Months Ended
	Aug. 31, 2002	Sep. 30, 2005
Debt Instrument [Line Items]
Frequency of periodic payment	semi-annual
Maturity date	February 2027
Guarantor obligations (as a percent)	50.00%
Basis spread on variable rate (as a percent)	0.20%
Interest rate (as a percent)		4.93%

Long-Term Debt - Nordea Credit Agreement (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Apr. 30, 2015	Sep. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2015	Sep. 30, 2013
Debt Instrument [Line Items]
Funded amount			$ 0	$ 250,000	$ 0
Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Notional amount							$ 148,100
Nordea Q5000 Loan Maturing April 2020 [Member]
Debt Instrument [Line Items]
Borrowing capacity		$ 250,000
Funded amount	$ 250,000
Maturity date		Apr. 30, 2020
Scheduled principal installments		$ 8,900
Frequency of periodic payment		quarterly
Balloon payment		$ 80,400
Nordea Q5000 Loan Maturing April 2020 [Member] \| Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Notional amount						$ 187,500
Fixed LIBOR rate on interest rate swaps (as a percent)						1.50%
Nordea Q5000 Loan Maturing April 2020 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)		2.50%

Long-Term Debt - Maturities Of Long-Term Debt (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Aug. 31, 2002	Dec. 31, 2016	Nov. 01, 2016	Dec. 31, 2015	Mar. 31, 2012
Debt Instrument [Line Items]
Less than one year		$ 67,571
One to two years		208,870
Two to three years		42,572
Three to four years		96,486
Four to five years		7,560
Over five years		233,965
Total debt		657,024
Less current maturities		(67,571)		$ (71,640)
Long-term debt, less current maturities		589,453
Unamortized debt discounts		(19,094)
Unamortized debt issuance costs		(11,963)		(11,993)
Long-term debt		558,396		677,695
Term Loan Maturing June 2018 [Member]
Debt Instrument [Line Items]
Less than one year		25,634
One to two years		166,624
Two to three years		0
Three to four years		0
Four to five years		0
Over five years		0
Total debt		192,258		255,000
Less current maturities		(25,634)
Long-term debt, less current maturities		166,624
Unamortized debt discounts		0
Unamortized debt issuance costs		(1,391)
Long-term debt		165,233
Convertible Senior Notes Maturing May 2022 [Member]
Debt Instrument [Line Items]
Less than one year		0
One to two years		0
Two to three years		0
Three to four years		0
Four to five years		0
Over five years		125,000
Total debt		125,000	$ 125,000	0
Less current maturities		0
Long-term debt, less current maturities		125,000
Unamortized debt discounts		(16,513)	$ (16,900)
Unamortized debt issuance costs		(2,790)
Long-term debt		105,697
Convertible Senior Notes Maturing March 2032 [Member]
Debt Instrument [Line Items]
Less than one year		0
One to two years		0
Two to three years		0
Three to four years		0
Four to five years		0
Over five years		60,115
Total debt		60,115		200,000	$ 200,000
Less current maturities		0
Long-term debt, less current maturities		60,115
Unamortized debt discounts		(2,581)		(14,963)	$ (35,400)
Unamortized debt issuance costs		(231)
Long-term debt		$ 57,303
Maturity date		March 2032
MARAD Debt Maturing February 2027 [Member]
Debt Instrument [Line Items]
Less than one year		$ 6,222
One to two years		6,532
Two to three years		6,858
Three to four years		7,200
Four to five years		7,560
Over five years		48,850
Total debt		83,222		89,148
Less current maturities		(6,222)
Long-term debt, less current maturities		77,000
Unamortized debt discounts		0
Unamortized debt issuance costs		(5,001)
Long-term debt		71,999
Maturity date	February 2027
Nordea Q5000 Loan Maturing April 2020 [Member]
Debt Instrument [Line Items]
Less than one year		35,715
One to two years		35,714
Two to three years		35,714
Three to four years		89,286
Four to five years		0
Over five years		0
Total debt		196,429		$ 232,143
Less current maturities		(35,715)
Long-term debt, less current maturities		160,714
Unamortized debt discounts		0
Unamortized debt issuance costs		(2,550)
Long-term debt		$ 158,164

Long-Term Debt - Interest Expense And Capitalized Interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
Interest expense	$ 45,110	$ 40,024	$ 33,064
Interest income	(2,086)	(2,068)	(4,786)
Capitalized interest	(11,785)	(11,042)	(10,419)
Net interest expense	$ 31,239	$ 26,914	$ 17,859

Income Taxes - Schedule Of Components Of Income Tax Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Current	$ (27,319)	$ 1,832	$ 43,817
Deferred	14,849	(103,022)	23,154
Income tax provision (benefit)	$ (12,470)	$ (101,190)	$ 66,971

Income Taxes - Schedule Of Components Of Income Tax Provision (Benefit) By Jurisdiction (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic	$ (9,631)	$ (102,978)	$ 29,613
Foreign	(2,839)	1,788	37,358
Income tax provision (benefit)	$ (12,470)	$ (101,190)	$ 66,971

Income Taxes - Schedule Of Components Of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic	$ (61,484)	$ (485,760)	$ 73,700
Foreign	(32,431)	7,590	188,821
Income (loss) before income taxes	$ (93,915)	$ (478,170)	$ 262,521

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Statutory rate		35.00%	35.00%	35.00%
Valuation allowance		$ 3,771	$ 1,936
Undistributed earnings of foreign subsidiaries		74,900	$ 304,000
Unrecognized tax benefits		300
Unrecognized tax benefits, decrease resulting from settlements with taxing authorities				$ 3,400
Income tax examination, reversal of penalties and interest accrued				$ 1,300
Income tax refunds	$ 35,200	28,400
U.S. [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward		43,200
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		7,200
Foreign [Member] \| Well Intervention [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward		3,200
Foreign [Member] \| Expiration 2025 [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		2,800
Foreign [Member] \| Expiration 2026 [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		$ 4,400

Income Taxes - Schedule Of Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory rate	35.00%	35.00%	35.00%
Foreign provision (as a percent)	(5.10%)	(13.70%)	(9.10%)
Goodwill impairment (as a percent)	(16.80%)	0.00%	0.00%
Other (as a percent)	0.20%	(0.10%)	(0.40%)
Effective rate (as a percent)	13.30%	21.20%	25.50%

Income Taxes - Schedule Of Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax liabilities:
Depreciation	$ 192,777	$ 173,863
Original issuance discount on 2022 Notes and 2032 Notes	11,802	17,957
Equity investments in production facilities	0	8,029
Prepaid and other	1,448	1,883
Total deferred tax liabilities	206,027	201,732
Deferred tax assets:
Net operating losses	(20,910)	(23,595)
Reserves, accrued liabilities and other	(38,131)	(52,672)
Total deferred tax assets	(59,041)	(76,267)
Valuation allowance	3,771	1,936
Net deferred tax liabilities	150,757	127,401
Current deferred tax assets	(16,594)	(53,573)
Non-current deferred tax liabilities	$ 167,351	$ 180,974

Income Taxes - Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at end of period	$ 300
Helix [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	0	$ 0	$ 4,723
Additions for tax positions of prior years	343	0	0
Reductions for tax positions of prior years	0	0	(4,723)
Balance at end of period	$ 343	$ 0	$ 0

Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 10, 2017	Aug. 11, 2016	Apr. 25, 2016
Class of Stock [Line Items]
Common stock, shares authorized		240,000,000	240,000,000
Preferred stock, shares authorized		5,000,000
Preferred stock, par value per share (in dollars per share)		$ 0.01
Net proceeds from issuance of common stock		$ 96,547	$ 0	$ 0
April ATM Program [Member]
Class of Stock [Line Items]
Maximum value of common stock to be issued							$ 50,000
Value of common stock issued		50,000
Net proceeds from issuance of common stock		47,700
Payments for commissions		$ 1,300
April ATM Program [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Shares issued		6,309,355
Price per share issued (in dollars per share)		$ 7.92
August ATM Program [Member]
Class of Stock [Line Items]
Maximum value of common stock to be issued						$ 50,000
Value of common stock issued		$ 50,000
Net proceeds from issuance of common stock		48,800
Payments for commissions		$ 1,000
August ATM Program [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Shares issued		6,709,377
Price per share issued (in dollars per share)		$ 7.45
Underwritten Public Equity Offering [Member] \| Common Stock [Member] \| Subsequent Event [Member]
Class of Stock [Line Items]
Shares issued					26,450,000
Price per share issued (in dollars per share)					$ 8.65
Net proceeds from issuance of common stock	$ 220,000

Shareholders' Equity - Components Of Accumulated OCI (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Cumulative foreign currency translation adjustment	$ (78,953)	$ (43,010)
Unrealized loss on hedges, net	(18,021)	(27,891)
Accumulated other comprehensive loss	(96,974)	(70,901)
Deferred income taxes	$ 9,700	$ 15,100

Stock Buyback Program (Details)	12 Months Ended
Stock Buyback Program (Details)	Dec. 31, 2016 shares
Equity [Abstract]
Total shares repurchased (in shares)	3,589,425
Remaining number of shares available to be repurchased	2,327,608

Earnings Per Share - Computation Of Basic And Diluted EPS (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Basic:
Net income (loss) applicable to common shareholders	$ (54,413)	$ 11,462	$ (10,671)	$ (27,823)	$ (403,867)	$ 9,880	$ (2,635)	$ 19,642	$ (81,445)	$ (376,980)	$ 195,047
Less: Undistributed earnings allocated to participating securities									0	0	(1,018)
Undistributed earnings (loss) allocated to common shares									$ (81,445)	$ (376,980)	$ 194,029
Weighted average number of shares outstanding - basic (in shares)									111,612	105,416	105,029
Effect of dilutive securities:
Undistributed earnings (loss) allocated to common shares									$ (81,445)	$ (376,980)	$ 194,029
Share-based awards other than participating securities									$ 0	$ 0	$ 0
Share-based awards other than participating securities (in shares)									0	0	16
Undistributed earnings reallocated to participating securities									$ 0	$ 0	$ 0
Net income (loss) applicable to common shareholders									$ (81,445)	$ (376,980)	$ 194,029
Weighted average number of shares outstanding, diluted									111,612	105,416	105,045

Earnings Per Share - Excluded Securities On Diluted Shares Calculation (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Diluted shares (as reported)	111,612	105,416	105,045
Total (in shares)	112,052	105,475
Share-Based Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	440	59

Earnings Per Share - Potentially Dilutive Shares Excluded From Dilutive EPS Calculation (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Convertible Senior Notes Maturing May 2022 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	1,475	0	0
Convertible Senior Notes Maturing March 2032 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	6,891	7,995	7,995

Employee Benefit Plans - Narrative (Details)	1 Months Ended		12 Months Ended
Employee Benefit Plans - Narrative (Details)	Jan. 31, 2017 USD ($) $ / shares shares	Feb. 29, 2016 shares	Dec. 31, 2016 USD ($) long-term_incentive_stock-based_plan $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Jan. 31, 2016 USD ($)	Jan. 31, 2015 USD ($)	Dec. 31, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number \| shares			1,577,973	661,124	554,960			771,942
Number of stock plans \| long-term_incentive_stock-based_plan			1
Granted (in shares) \| shares			1,298,121	501,076	139,455
Grants in period (in shares) \| shares			1,161,672	295,693	73,609
Grant date fair value (in dollars per share) \| $ / shares			$ 7.13	$ 25.06	$ 26.79
Deferred compensation arrangement with individual award vesting period			3 years
Long-term incentive cash awards granted			$ 0		$ 8,900,000
Compensation expense					7,200,000
Deferred compensation cash-based arrangement, liability			$ 0	$ 100,000
Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense					3,600,000
Adjustment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense				(3,700,000)
Adjustment [Member] \| Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense				(2,100,000)
E S P P [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares) \| shares			1,500,000
Shares available for issuance (in shares) \| shares			700,000
Period common stock may be purchased through payroll deductions			4 months
Percentage of share of non-vested stock considered as call option			85.00%
Allocated share-based compensation expense			$ 100,000	1,100,000	$ 1,000,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase limit per employee (in shares) \| shares		130
2005 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares) \| shares			10,300,000
Shares available for issuance (in shares) \| shares			3,700,000
Awards granted vesting percentage			33.00%
Vesting period			3 years
2005 Incentive Plan [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) \| shares	671,771
Market value per share (in dollars per share) \| $ / shares	$ 8.82
Future compensation expense	$ 5,900,000
Grants in period (in shares) \| shares	671,771
2005 Incentive Plan [Member] \| Maximum Shares As Incentive Options Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance (in shares) \| shares			2,000,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number \| shares					33,760
Long-term incentive cash awards paid							$ 700,000
Restricted Stock Units and Restricted Stock Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost			$ 5,800,000	5,500,000	$ 5,000,000
Forfeiture on restricted stock percentage			5.00%
Forfeiture on restricted stock period			5 years
Future compensation expense			$ 7,500,000
Weighted average vesting period			1 year 11 months
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted vesting percentage			100.00%
Compensation cost			$ 6,800,000	200,000	5,400,000
Vesting period			3 years
Recorded liability			$ 7,100,000	700,000
Long-term incentive cash awards paid						$ 200,000	$ 4,500,000
Performance Shares [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award percentage			200.00%
Performance Shares [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award percentage			0.00%
Performance Shares [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term incentive cash awards paid	$ 600,000
Modified Liability Performance Share [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense in excess of fair value recorded in equity			$ 200,000	2,900,000
Long-Term Incentive Cash Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term incentive cash awards paid				8,900,000	$ 9,200,000
401K Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer matching contribution (as a percent)					75.00%
Matching contribution percent of employees' salary (up to)					5.00%
Cost of plan			$ 500,000	$ 2,800,000	$ 2,200,000

Employee Benefit Plans - Restricted Shares Granted (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares	1,298,121	501,076	139,455
January 4, 2016 - 33% per year over three years [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Jan. 04, 2016
Shares	1,143,062
Grant Date Fair Value Per Share	$ 5.26
Vesting Percentage	33.00%
Vesting Period	3 years
January 4, 2016 - 100% on January 1, 2019 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Jan. 04, 2016
Shares	1,143,062
Grant Date Fair Value Per Share	$ 7.13
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2019
January 4, 2016 - 100% on January 1, 2018 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Jan. 04, 2016
Shares	11,763
Grant Date Fair Value Per Share	$ 5.26
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2018
February 1, 2016 - 33% per year over three years [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Feb. 01, 2016
Shares	18,610
Grant Date Fair Value Per Share	$ 4.03
Vesting Percentage	33.00%
Vesting Period	3 years
February 1, 2016 - 100% on January 1, 2019 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Feb. 01, 2016
Shares	18,610
Grant Date Fair Value Per Share	$ 7.13
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2019
April 1, 2016 - 100% on January 1, 2018 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Apr. 01, 2016
Shares	13,727
Grant Date Fair Value Per Share	$ 5.60
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2018
July 1, 2016 - 100% on January 1, 2018 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Jul. 01, 2016
Shares	8,476
Grant Date Fair Value Per Share	$ 6.76
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2018
October 3, 2016 - 100% on January 1, 2018 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Oct. 03, 2016
Shares	7,803
Grant Date Fair Value Per Share	$ 8.13
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2018
December 2, 2016 - 100% on January 1, 2018 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Dec. 02, 2016
Shares	94,680
Grant Date Fair Value Per Share	$ 11.09
Vesting Percentage	33.00%
Vesting Period	3 years

Employee Benefit Plans - Schedule Of Restricted Stock And Restricted Stock Units Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 31, 2015
Shares
Awards outstanding at beginning of year (in shares)	661,124	554,960	771,942
Granted (in shares)	1,298,121	501,076	139,455
Vested (in shares)	(305,588)	(332,223)	(356,437)
Forfeited (in shares)	(75,684)	(62,689)	0
Awards outstanding at end of year (in shares)	1,577,973	661,124	554,960
Grant Date Fair Value
Awards outstanding at beginning of year (in dollars per share)	$ 16.28	$ 17.54	$ 13.62
Granted (in dollars per share)	5.70	15.57	23.22
Vested (in dollars per share)	16.94	16.44	11.27
Forfeited (in dollars per share)	7.76	20.93	0.00
Awards outstanding at end of year (in dollars per share)	$ 7.86	$ 16.28	$ 17.54
Fair value of awards vested	$ 2.2	$ 5.1	$ 8.2
Restricted Stock Units (RSUs) [Member]
Shares
Awards outstanding at beginning of year (in shares)		33,760
Awards outstanding at end of year (in shares)			33,760
Grant Date Fair Value
Awards outstanding at beginning of year (in dollars per share)		$ 15.80
Awards outstanding at end of year (in dollars per share)			$ 15.80
Long-term incentive cash awards paid				$ 0.7

Business Segment Information - Narrative (Details)	12 Months Ended
Business Segment Information - Narrative (Details)	Dec. 31, 2016 segment vessel
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	3
Robotics [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels \| vessel	3

Business Segment Information - Summary Of Financial Data By Segment (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	Dec. 31, 2016	Jan. 31, 2014	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues			$ 128,031	$ 161,245	$ 107,267	$ 91,039	$ 157,683	$ 182,462	$ 166,016	$ 189,641	$ 487,582	$ 695,802	$ 1,107,156
Income (loss) from operations											(63,235)	(307,360)	261,756
Net interest expense											31,239	26,914	17,859
Equity in earnings (losses) of investments											(2,166)	(124,345)	879
Income (loss) before income taxes											(93,915)	(478,170)	262,521
Income tax provision (benefit)											(12,470)	(101,190)	66,971
Capital expenditures											186,487	320,311	336,912
Depreciation and amortization											114,187	120,401	109,345
Asset impairment charges											0	345,010	0
Goodwill impairment charge											45,107	16,399	0
Gain on disposition of assets, net											1,290	92	10,240
Unrealized losses on foreign exchange contracts							19,000				(8,800)	18,281	1,320
Proceeds from insurance reimbursement													7,200
United Kingdom [Member]
Segment Reporting Information [Line Items]
Net revenues											123,600	187,700	362,700
Helix 534 [Member]
Segment Reporting Information [Line Items]
Asset impairment charges							205,200					205,200
Gain on disposition of assets, net											1,300
Capitalized Vessel Project Costs [Member]
Segment Reporting Information [Line Items]
Impairment charges to write off capitalized costs							6,300					6,300
HP I [Member]
Segment Reporting Information [Line Items]
Asset impairment charges							133,400					133,400
Reportable Segments [Member] \| Spoolbase Facility [Member]
Segment Reporting Information [Line Items]
Gain on disposition of assets, net		$ 10,500
Intercompany Elimination [Member]
Segment Reporting Information [Line Items]
Net revenues											(39,356)	(54,473)	(74,450)
Income (loss) from operations											(372)	(98)	(921)
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations											(39,384)	(33,866)	(51,600)
Income (loss) before income taxes											(70,890)	(55,475)	(51,862)
Income tax provision (benefit)											(26,146)	(19,423)	(19,138)
Capital expenditures											(199)	(135)	1,060
Corporate and Eliminations [Member]
Segment Reporting Information [Line Items]
Net interest expense											31,373	26,602	17,732
Depreciation and amortization											5,995	6,242	6,019
Other income													16,900
Proceeds from insurance reimbursement													7,200
Well Intervention [Member]
Segment Reporting Information [Line Items]
Goodwill impairment charge							$ 16,400				0	16,399
Well Intervention [Member] \| United Kingdom [Member]
Segment Reporting Information [Line Items]
Goodwill impairment charge												16,400
Well Intervention [Member] \| Helix 534 [Member]
Segment Reporting Information [Line Items]
Asset impairment charges												205,200
Gain on disposition of assets, net	$ 1,300
Well Intervention [Member] \| Capitalized Vessel Project Costs [Member]
Segment Reporting Information [Line Items]
Impairment charges to write off capitalized costs												6,300
Well Intervention [Member] \| Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net revenues											294,000	373,301	667,849
Income (loss) from operations											14,910	(194,381)	204,810
Net interest expense											(109)	(102)	(252)
Income (loss) before income taxes											18,813	(193,572)	211,725
Income tax provision (benefit)											12,531	(1,230)	50,102
Capital expenditures											185,892	307,879	283,635
Depreciation and amortization											68,392	66,095	57,570
Well Intervention [Member] \| Intercompany Elimination [Member]
Segment Reporting Information [Line Items]
Net revenues											(8,442)	(22,855)	(29,875)
Robotics [Member]
Segment Reporting Information [Line Items]
Goodwill impairment charge			$ 45,100								45,107	0
Unrealized losses on foreign exchange contracts												18,300
Robotics [Member] \| Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net revenues											160,580	301,026	420,224
Income (loss) from operations											(72,250)	27,832	68,329
Net interest expense											(25)	29	(5)
Income (loss) before income taxes											(73,533)	2,454	61,025
Income tax provision (benefit)											(9,948)	515	21,612
Capital expenditures											720	10,700	51,348
Depreciation and amortization											25,848	26,724	24,478
Robotics [Member] \| Intercompany Elimination [Member]
Segment Reporting Information [Line Items]
Net revenues											(30,914)	(31,618)	(44,575)
Production Facilities [Member] \| HP I [Member]
Segment Reporting Information [Line Items]
Asset impairment charges												133,400
Production Facilities [Member] \| Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net revenues											72,358	75,948	93,175
Income (loss) from operations											33,861	(106,847)	41,138
Net interest expense											0	385	384
Income (loss) before income taxes											31,695	(231,577)	41,633
Income tax provision (benefit)											11,093	(81,052)	14,395
Capital expenditures											74	1,867	869
Depreciation and amortization											13,952	21,340	21,278
Other [Member] \| Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net revenues											$ 0	$ 0	$ 358

Business Segment Information - Summary Of Intercompany Segment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues	$ (128,031)	$ (161,245)	$ (107,267)	$ (91,039)	$ (157,683)	$ (182,462)	$ (166,016)	$ (189,641)	$ (487,582)	$ (695,802)	$ (1,107,156)
Intercompany Elimination [Member]
Segment Reporting Information [Line Items]
Net revenues									39,356	54,473	74,450
Intercompany Elimination [Member] \| Well Intervention [Member]
Segment Reporting Information [Line Items]
Net revenues									8,442	22,855	29,875
Intercompany Elimination [Member] \| Robotics [Member]
Segment Reporting Information [Line Items]
Net revenues									$ 30,914	$ 31,618	$ 44,575

Business Segment Information - Revenue By Geographical Region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Total net revenues	$ 128,031	$ 161,245	$ 107,267	$ 91,039	$ 157,683	$ 182,462	$ 166,016	$ 189,641	$ 487,582	$ 695,802	$ 1,107,156
United States [Member]
Segment Reporting Information [Line Items]
Total net revenues									298,279	298,391	403,994
North Sea [Member]
Segment Reporting Information [Line Items]
Total net revenues									137,313	263,438	504,016
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total net revenues									123,600	187,700	362,700
Other [Member]
Segment Reporting Information [Line Items]
Total net revenues									$ 51,990	$ 133,973	$ 199,146

Business Segment Information - Property And Equipment Net Of Accumulated Depreciation By Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Property and equipment, net	$ 1,651,610	$ 1,603,009
United States [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	956,458	1,024,691
United Kingdom [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	299,699	352,740
Singapore [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	194,649	112,313
Other [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	$ 200,804	$ 113,265

Business Segment Information - Total Assets By Reportable Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total assets	$ 2,246,941	$ 2,399,959
Reportable Segments [Member] \| Well Intervention [Member]
Segment Reporting Information [Line Items]
Total assets	1,596,517	1,484,109
Reportable Segments [Member] \| Robotics [Member]
Segment Reporting Information [Line Items]
Total assets	186,901	274,926
Reportable Segments [Member] \| Production Facilities [Member]
Segment Reporting Information [Line Items]
Total assets	158,192	182,007
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total assets	$ 305,331	$ 458,917

Commitments And Contingencies And Other Matters - Narrative (Details) $ in Thousands	1 Months Ended						12 Months Ended
	Oct. 21, 2016 USD ($)	Jan. 31, 2016 USD ($) renewal_option	Dec. 31, 2015 USD ($) payment_installment	Jul. 31, 2015 USD ($)	Feb. 28, 2014 vessel	Sep. 30, 2013 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Nov. 30, 2014 USD ($)
Commitments And Contingencies [Line Items]
Total investment			$ 2,544,857				$ 2,450,890	$ 2,544,857
Charter fee deposit			$ 12,544				12,544	12,544
Total rental expense							87,800	134,300	$ 147,200
Total rental income							1,600	$ 1,400	$ 800
Minimum rentals to be received in the future							2,000
Scotland [Member]
Commitments And Contingencies [Line Items]
Term of lease agreement		15 years
Number of renewal options \| renewal_option		2
Term of renewal option		5 years
Annual minimum lease payment		$ 800
Q7000 [Member]
Commitments And Contingencies [Line Items]
Contract amount						$ 346,000
Percentage of contract price paid			80.00%
Number of installments to be paid \| payment_installment			3
Total investment							194,600
Payment of shipyard costs	$ 69,200
Q7000 [Member] \| Contract Signing [Member]
Commitments And Contingencies [Line Items]
Percentage of contract price paid						20.00%
Payment of shipyard costs							69,200
Q7000 [Member] \| Due June 2016 [Member]
Commitments And Contingencies [Line Items]
Percentage of contract price paid			20.00%
Q7000 [Member] \| Issuance of Completion Certificate [Member]
Commitments And Contingencies [Line Items]
Percentage of contract price paid			20.00%
Q7000 [Member] \| Vessel Delivery [Member]
Commitments And Contingencies [Line Items]
Percentage of contract price paid			40.00%
Q7000 [Member] \| Capital Addition Purchase Commitments [Member] \| Extend Scheduled Delivery [Member]
Commitments And Contingencies [Line Items]
Total investment										$ 14,500
Q7000 [Member] \| Capital Addition Purchase Commitments [Member] \| Contract Signing [Member] \| Extend Scheduled Delivery [Member]
Commitments And Contingencies [Line Items]
Payment of shipyard costs				$ 7,300
Monohull Vessels [Member]
Commitments And Contingencies [Line Items]
Number of chartered vessels \| vessel					2
Topside Equipment [Member]
Commitments And Contingencies [Line Items]
Total investment							$ 200,700
Siem Helix 2 [Member]
Commitments And Contingencies [Line Items]
Charter fee deposit											$ 12,500
Siem [Member] \| Monohull Vessels [Member]
Commitments And Contingencies [Line Items]
Term of charter agreement					7 years
Petrobras [Member]
Commitments And Contingencies [Line Items]
Term of contract					4 years

Commitments And Contingencies And Other Matters - Lease Commitments (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	$ 162,234
2018	147,570
2019	136,788
2020	116,403
2021	104,230
Thereafter	169,427
Total lease commitments	836,652
Vessels [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	156,446
2018	142,407
2019	131,665
2020	111,650
2021	99,563
Thereafter	149,861
Total lease commitments	791,592
Facilities and Other [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	5,788
2018	5,163
2019	5,123
2020	4,753
2021	4,667
Thereafter	19,566
Total lease commitments	$ 45,060

Statement Of Cash Flow Information - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
Interest paid, net of interest capitalized	$ 18,749	$ 14,555	$ 11,628
Income taxes paid	$ 5,635	$ 16,905	$ 70,509

Statement Of Cash Flow Information - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
Non-cash capital expenditures	$ 10.1	$ 18.7
Non-cash transaction			$ 27.5

Allowance Accounts - Summary Of Activity In Valuation Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation Allowance, Operating Loss Carryforwards [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Adjustments		$ (20,600)
Allowance for Uncollectible Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of period	$ 350	4,735	$ 2,234
Additions	1,778	3,275	5,331
Deductions	(350)	(7,660)	(2,830)
Adjustments	0	0	0
Balance at the end of period	1,778	350	4,735
Deferred Tax Asset Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of period	1,936	23,076	22,860
Additions	0	0	0
Deductions	0	0	0
Adjustments	1,835	(21,140)	216
Balance at the end of period	$ 3,771	$ 1,936	$ 23,076

Allowance Accounts - Narrative (Details) $ in Millions	Dec. 31, 2016 USD ($)
Valuation and Qualifying Accounts [Abstract]
Allowance for note receivable	$ 4.2

Fair Value Measurements - Assets And Liabilities Measured At Fair Value On A Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total net liability	$ 38,470	$ 62,487
Foreign Exchange Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	38,170	61,427
Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	751	1,473
Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	451	413
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total net liability	0	0
Fair Value, Inputs, Level 1 [Member] \| Foreign Exchange Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Fair Value, Inputs, Level 1 [Member] \| Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Fair Value, Inputs, Level 1 [Member] \| Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total net liability	38,470	62,487
Fair Value, Inputs, Level 2 [Member] \| Foreign Exchange Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	38,170	61,427
Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	751	1,473
Fair Value, Inputs, Level 2 [Member] \| Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	451	413
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total net liability	0	0
Fair Value, Inputs, Level 3 [Member] \| Foreign Exchange Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Fair Value, Inputs, Level 3 [Member] \| Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 0	$ 0

Fair Value Measurements - Carrying Values And Estimated Fair Values Of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Nov. 01, 2016	Dec. 31, 2015	Mar. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value	$ 657,024
Term Loan Maturing June 2018 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value	192,258		$ 255,000
Fair value	192,258		248,467
Nordea Q5000 Loan Maturing April 2020 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value	196,429		232,143
Fair value	192,746		221,553
MARAD Debt Maturing February 2027 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value	83,222		89,148
Fair value	92,049		104,897
Convertible Senior Notes Maturing May 2022 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value	125,000	$ 125,000	0
Fair value	130,156		0
Convertible Senior Notes Maturing March 2032 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value	60,115		200,000	$ 200,000
Fair value	59,965		150,250
Loan Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value	657,024		776,291
Fair value	$ 667,174		$ 725,167

Derivative Instruments And Hedging Activities - Derivative Instruments Designated As Hedging Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Asset derivative instruments designated as hedging instruments	$ 451	$ 413
Liability derivative instruments designated as hedging instruments	28,190	44,886
Other Assets, Net [Member] \| Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Asset derivative instruments designated as hedging instruments	451	413
Accrued Liabilities [Member] \| Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Liability derivative instruments designated as hedging instruments	751	1,473
Accrued Liabilities [Member] \| Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability derivative instruments designated as hedging instruments	14,056	14,955
Other Non-Current Liabilities [Member] \| Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability derivative instruments designated as hedging instruments	$ 13,383	$ 28,458

Derivative Instruments And Hedging Activities - Derivative Instruments Not Designated As Hedging Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	$ 10,731	$ 18,014
Accrued Liabilities [Member] \| Foreign Exchange Contracts [Member]
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	3,923	6,763
Other Non-Current Liabilities [Member] \| Foreign Exchange Contracts [Member]
Derivative [Line Items]
Liability derivative instruments not designated as hedging instruments	$ 6,808	$ 11,251

Derivative Instruments And Hedging Activities - Narrative (Details) $ in Thousands, kr in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2015 NOK (kr)	Jun. 30, 2015 USD ($)	Sep. 30, 2013 USD ($)	Feb. 28, 2013 USD ($)	Feb. 28, 2013 NOK (kr)	Jan. 31, 2013 USD ($)	Jan. 31, 2013 NOK (kr)
Derivative [Line Items]
Unrealized loss on hedges, net	$ 27,891	$ 18,021	$ 27,891
Unrealized losses related to foreign exchange contracts	18,000
Loss in Accumulated OCI to be reclassified within twelve months		9,600
Grand Canyon [Member]
Derivative [Line Items]
Notional amount										$ 104,600	kr 591.3
Grand Canyon II [Member]
Derivative [Line Items]
Notional amount					kr 434.1			$ 100,400	kr 594.7
Grand Canyon III [Member]
Derivative [Line Items]
Notional amount					kr 185.2			$ 98,800	kr 595.0
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional amount							$ 148,100
Interest Rate Swaps [Member] \| Nordea Q5000 Loan Maturing April 2020 [Member]
Derivative [Line Items]
Notional amount						$ 187,500
Cash Flow Hedging [Member] \| Foreign Exchange Contracts [Member]
Derivative [Line Items]
Unrealized loss on hedges, net	$ 19,800		19,800
Other Income (Expense), Net [Member] \| Grand Canyon [Member]
Derivative [Line Items]
Realized loss on hedge ineffectiveness		(100)
Unrealized loss on hedge ineffectiveness		$ 0	1,500
Other Income (Expense), Net [Member] \| Grand Canyon II [Member]
Derivative [Line Items]
Realized loss on hedge ineffectiveness				$ 500
Unrealized loss on hedge ineffectiveness				$ 1,200
Other Income (Expense), Net [Member] \| Grand Canyon II and Grand Canyon III [Member]
Derivative [Line Items]
Realized loss on hedge ineffectiveness			$ 3,600

Derivative Instruments And Hedging Activities - Impact Of Derivative Instruments Designated As Hedging Instruments On Accumulated OCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative Instruments, Net of Tax (Effective Portion)	$ 9,870	$ 4,200	$ (22,100)
Foreign Exchange Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative Instruments, Net of Tax (Effective Portion)	9,397	4,734	(22,170)
Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative Instruments, Net of Tax (Effective Portion)	$ 473	$ (534)	$ 70

Derivative Instruments And Hedging Activities - Loss Reclassified From Accumulated OCI Into Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Loss Reclassified from Accumulated OCI into Earnings (Effective Portion)	$ (12,851)	$ (13,659)	$ (3,365)
Foreign Exchange Contracts [Member] \| Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Reclassified from Accumulated OCI into Earnings (Effective Portion)	(10,827)	(11,516)	(2,507)
Interest Rate Swaps [Member] \| Net Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Reclassified from Accumulated OCI into Earnings (Effective Portion)	$ (2,024)	$ (2,143)	$ (858)

Derivative Instruments And Hedging Activities - Impact Of Derivative Instruments Not Designated As Hedging Instruments On Consolidated Statement Of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Earnings on Derivative Instruments	$ 1,198	$ (18,014)	$ 7
Foreign Exchange Contracts [Member] \| Other Income (Expense), Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Earnings on Derivative Instruments	$ 1,198	$ (18,014)	$ 7

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 128,031	$ 161,245	$ 107,267	$ 91,039	$ 157,683	$ 182,462	$ 166,016	$ 189,641	$ 487,582	$ 695,802	$ 1,107,156
Gross profit (loss)	17,604	40,184	5,658	(16,930)	(324,898)	31,969	24,208	34,947	46,516	(233,774)	344,036
Net income (loss) applicable to common shareholders	$ (54,413)	$ 11,462	$ (10,671)	$ (27,823)	$ (403,867)	$ 9,880	$ (2,635)	$ 19,642	$ (81,445)	$ (376,980)	$ 195,047
Basic earnings (loss) per common share (in dollars per share)	$ (0.46)	$ 0.10	$ (0.10)	$ (0.26)	$ (3.83)	$ 0.09	$ (0.03)	$ 0.19	$ (0.73)	$ (3.58)	$ 1.85
Diluted earnings (loss) per common share (in dollars per share)	$ (0.46)	$ 0.10	$ (0.10)	$ (0.26)	$ (3.83)	$ 0.09	$ (0.03)	$ 0.19	$ (0.73)	$ (3.58)	$ 1.85
Quarterly Financial Information [Line Items]
Asset impairment charges									$ 0	$ 345,010	$ 0
Goodwill impairment									45,107	16,399	0
Loss from equity method investments									2,166	124,345	(879)
Unrealized losses on foreign exchange contracts					$ 19,000				(8,800)	18,281	$ 1,320
Deepwater Gateway LLC and Independence Hub LLC [Member]
Quarterly Financial Information [Line Items]
Loss from equity method investments					123,800
Robotics [Member]
Quarterly Financial Information [Line Items]
Goodwill impairment	$ 45,100								45,107	0
Unrealized losses on foreign exchange contracts										18,300
Well Intervention [Member]
Quarterly Financial Information [Line Items]
Goodwill impairment					16,400				$ 0	16,399
Helix 534 [Member]
Quarterly Financial Information [Line Items]
Asset impairment charges					205,200					205,200
Helix 534 [Member] \| Well Intervention [Member]
Quarterly Financial Information [Line Items]
Asset impairment charges										205,200
HP I [Member]
Quarterly Financial Information [Line Items]
Asset impairment charges					133,400					133,400
Capitalized Vessel Project Costs [Member]
Quarterly Financial Information [Line Items]
Impairment charges to write off capitalized costs					$ 6,300					6,300
Capitalized Vessel Project Costs [Member] \| Well Intervention [Member]
Quarterly Financial Information [Line Items]
Impairment charges to write off capitalized costs										$ 6,300