Long-Term Debt - Additional Information (Details)											1 Months Ended	3 Months Ended	12 Months Ended									24 Months Ended	72 Months Ended
	Oct. 01, 2017	Sep. 01, 2017	Apr. 01, 2017	Mar. 01, 2017	Mar. 14, 2013 USD ($)	Aug. 13, 2012 USD ($) $ / shares	Aug. 13, 2012 USD ($) $ / shares	Apr. 30, 2012 USD ($)	Mar. 16, 2012 USD ($)	Mar. 02, 2012 USD ($)	Aug. 07, 2012 $ / shares	Sep. 30, 2017 USD ($)	Jun. 15, 2021	Jun. 15, 2020	Jun. 15, 2019	Jun. 15, 2018	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Jun. 15, 2023	Jun. 15, 2023	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 16, 2017 USD ($)	Jun. 15, 2017 USD ($)
Debt Instrument [Line Items]
Deferred Finance Costs, Net																	$ 10,134,000	$ 10,197,000
Debt Instrument, Principal amount																	1,079,911,000	1,125,000,000
First-Lien Credit Facility Covenant Minimum Delayed Draw Commitment																	67,000,000
GainOnExchangeOfDebtInstrument												$ 20,700,000
Repayments of Senior Debt																	5,057,000	0	$ 0
Gain (Loss) on Extinguishment of Debt																	$ 15,478,000	0	0	$ (25,800,000)	$ (6,000,000)
Proceeds from Convertible Debt						$ 300,000,000
Debt Instrument, Convertible, Conversion Ratio							18.5718
Conversion Price per Share | $ / shares						$ 53.85	$ 53.85
Market Price Per Share | $ / shares											$ 39.16
Repurchase Price As Percentage Of Principal Amount Of Senior Notes																	100.00%
Proceeds from Issuance of Warrants						$ 48,200,000
Purchase Of Convertible Note Hedges						73,000,000
Debt, Fair Value																	$ 717,955,000	788,476,000
Capitalized interest, approximate amount																	10,200,000	16,700,000	$ 24,700,000
First-Lien Credit Facility Maturing Twenty Twenty Three [Member] [Domain]
Debt Instrument [Line Items]
First Lien Credit Facility, Current Borrowing Capacity																											$ 300,000,000
Deferred Finance Costs, Net																	3,445,000
Debt Instrument, Principal amount																	163,322,000	0
FirstLienCreditFacilityCovenantMinimumAvailableLiquidity																	25,000,000
First-Lien Credit Facility Covenant Minimum Liquidity For Prepayment																	65,000,000
Debt Instrument, Exchange Amount																											95,300,000
Letter of Credit																	177,560,000	0
Debt, Fair Value																	$ 162,505,000	$ 0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity																											75,000,000
Revolving credit facility, Current Borrowing Capacity																											200,000,000
Senior notes 6.125 Percent Due 2014
Debt Instrument [Line Items]
Percentage Of debt outstanding tendered								16.00%	84.00%
Senior Notes 8.000 Percent Due 2017
Debt Instrument [Line Items]
Percentage Of debt outstanding tendered					94.00%
Senior Notes 5.875 Percent Due 2020
Debt Instrument [Line Items]
Debt Interest Rate																	5.875%	5.875%
Deferred Finance Costs, Net																	$ 2,061,000	$ 3,025,000
Debt Instrument, Principal amount										$ 375,000,000							366,942,000	375,000,000
Proceeds from Issuance of Senior Long-term Debt										$ 367,400,000
Extinguishment of Debt, Amount																	8,100,000
Repayments of Senior Debt					$ 16,600,000			$ 49,500,000	$ 259,900,000
Debt Instrument Maturity Year																					2020
Debt Instrument, Maturity Date																					Apr. 01, 2020
Debt Instrument, Effective Interest Rate																					6.08%
Senior Notes																	364,881,000	371,975,000
Debt, Fair Value																	244,714,000	$ 270,938,000
Convertible One Point Five Percent Senior Notes Due Twenty Nineteen And Senior Notes Five Point Eight Seven Five Percent Due Twenty Twenty [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount																										$ 54,100,000
Extinguishment of Debt, Gain (Loss), Net of Tax																	$ 10,500,000
Extinguishment of Debt, Gain (Loss), Per Share, Net of Tax | $ / shares																	$ 0.29
Senior Notes 5.000 Percent Due 2021
Debt Instrument [Line Items]
Debt Interest Rate																	5.00%	5.00%
Deferred Finance Costs, Net																	$ 3,142,000	$ 4,111,000
Debt Instrument, Principal amount																	450,000,000	450,000,000
Debt Instrument Maturity Year																			2021
Debt Instrument, Maturity Date																			Mar. 01, 2021
Senior Notes																	446,858,000	445,889,000
Debt, Fair Value																	$ 236,250,000	$ 301,343,000
Convertible 5.000 Percent Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Principal amount					450,000,000
Proceeds from Issuance of Senior Long-term Debt					442,400,000
Repayments of Senior Debt					$ 252,700,000
Percentage Of debt outstanding tendered					6.00%
Debt Instrument, Effective Interest Rate					5.21%
Convertible 1.500 Percent Senior Notes Due 2019
Debt Instrument [Line Items]
Debt Interest Rate																	1.50%	1.50%
Deferred Finance Costs, Net																	$ 1,486,000	$ 3,061,000
Debt Instrument, Principal amount						300,000,000	$ 300,000,000										99,647,000	300,000,000
Proceeds from Issuance of Senior Long-term Debt						266,000,000
Debt Instrument, Exchanged Face Amount																											$ 127,100,000
Extinguishment of Debt, Amount																	$ 73,300,000
Debt Issuance Costs, Gross						$ 9,300,000	$ 9,300,000
Debt Instrument Maturity Year																	2019
Debt Instrument, Maturity Date							Sep. 01, 2019
Debt Instrument, Effective Interest Rate						6.23%	6.23%
Proceeds from Convertible Debt						$ 300,000,000
Discount Rate Used To Determine Liability Fair Value						5.75%	5.75%
Debt Instrument Convertible Carrying Amount Of Liability Component						$ 227,600,000	$ 227,600,000
Debt Instrument, Convertible, Carrying Amount of Equity Component						72,400,000	72,400,000
Debt Instrument Maturity Period																	7 years
Decrease In Additional Paid In Capital																					$ 2,200,000
Amortization Of Deferred Financing Costs To Interest Expense																	$ 7,100,000
Senior Notes																	91,527,000	265,846,000
Debt, Fair Value																	$ 74,486,000	$ 216,195,000
Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Proceeds from Convertible Debt						290,800,000
First Lien Credit Facility Number Of Vessels Used As Collateral [Member]
Debt Instrument [Line Items]
FirstLienCreditFacilityCollateralNumberOfVessels																											51
First Lien Credit Facility Number Of Newbuild MPSVs Used As Collateral [Member]
Debt Instrument [Line Items]
FirstLienCreditFacilityCollateralNumberOfVessels																											2
First Lien Credit Facility Unencumbered Low-Spec Domestic OSVs [Member]
Debt Instrument [Line Items]
First Lien Credit Facility Unencumbered Vessels																											10
First Lien Credit Facility Unencumbered Foreign-Flagged OSVs [Member]
Debt Instrument [Line Items]
First Lien Credit Facility Unencumbered Vessels																											11
Semi Annual Payment First Payment [Member] | Senior Notes 5.875 Percent Due 2020
Debt Instrument [Line Items]
Debt Instrument, Interest payable date			--04-01
Semi Annual Payment First Payment [Member] | Senior Notes 5.000 Percent Due 2021
Debt Instrument [Line Items]
Debt Instrument, Interest payable date				--03-01
Semi Annual Payment First Payment [Member] | Convertible 1.500 Percent Senior Notes Due 2019
Debt Instrument [Line Items]
Debt Instrument, Interest payable date				--03-01
Semi Annual Payment Second Payment [Member] | Senior Notes 5.875 Percent Due 2020
Debt Instrument [Line Items]
Debt Instrument, Interest payable date	--10-01
Semi Annual Payment Second Payment [Member] | Senior Notes 5.000 Percent Due 2021
Debt Instrument [Line Items]
Debt Instrument, Interest payable date		--09-01
Semi Annual Payment Second Payment [Member] | Convertible 1.500 Percent Senior Notes Due 2019
Debt Instrument [Line Items]
Debt Instrument, Interest payable date		--09-01
Warrant [Member] | Convertible 1.500 Percent Senior Notes Due 2019
Debt Instrument [Line Items]
Principal Amount Senior Notes for conversion						1,000	1,000
Debt Instrument Convertible Conversion Warrant Strike Price | $ / shares											$ 68.53
Debt Instrument Convertible Conversion Premium											75.00%
Conversion Condition Two [Member] | Convertible 1.500 Percent Senior Notes Due 2019
Debt Instrument [Line Items]
Principal Amount Senior Notes for conversion						$ 1,000	$ 1,000
Number Of Trading Days Whether Consecutive Or Not For First Condition Of Convertibility Of Notes							5 days
Number of consecutive trading days used in conversion analysis							10 days
Trading price per 1000 principal amount of notes, percent							95.00%
Conversion Condition One [Member] | Convertible 1.500 Percent Senior Notes Due 2019
Debt Instrument [Line Items]
Debt Instrument Conversion Circumstance Percentage Stock Price Of Stock Conversion Threshold							135.00%
Number of consecutive trading days used in conversion analysis							30 days
Minimum | Conversion Condition One [Member] | Convertible 1.500 Percent Senior Notes Due 2019
Debt Instrument [Line Items]
Number Of Trading Days Whether Consecutive Or Not For First Condition Of Convertibility Of Notes							20 days
Subsequent Event [Member]
Debt Instrument [Line Items]
First-Lien Credit Facility Covenant Minimum Delayed Draw Commitment																								$ 204,700,000	$ 136,000,000
Subsequent Event [Member] | First-Lien Credit Facility Maturing Twenty Twenty Three [Member] [Domain]
Debt Instrument [Line Items]
First-Lien Credit Facility Redemption Premium															101.00%	102.00%
Subsequent Event [Member] | First-Lien Credit Facility Maturing Twenty Twenty Three [Member] [Domain] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
First Lien Credit Facility Floor Interest Rate																							1.00%
FirstLienCreditFacilityBasisSpreadOnVariableRate													7.25%	7.00%	6.50%	6.00%						7.50%
Subsequent Event [Member] | First-Lien Credit Facility Maturing Twenty Twenty Three [Member] [Domain] | Prime Rate [Member]
Debt Instrument [Line Items]
FirstLienCreditFacilityBasisSpreadOnVariableRate													6.25%	6.00%	5.50%	5.00%						6.50%