Condensed Consolidating Guarantor Financial Information Condensed Consolidating Statement of Operations (Details) - USD ($)	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1],[2]	Sep. 30, 2017	[1],[2]	Jun. 30, 2017	[1],[2]	Mar. 31, 2017	[1],[2]	Dec. 31, 2016	[2]	Sep. 30, 2016	[2]	Jun. 30, 2016	[2]	Mar. 31, 2016	[2]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2012
Condensed Income Statements, Captions [Line Items]
Revenues	$ 56,241,000		$ 53,666,000		$ 37,426,000		$ 44,079,000		$ 41,879,000		$ 51,927,000		$ 53,673,000		$ 76,820,000		$ 191,412,000	$ 224,299,000	$ 476,070,000
Operating Costs and Expenses																	120,537,000	131,658,000	219,260,000
Depreciation																	98,733,000	93,071,000	82,566,000
Amortization of Deferred Charges																	13,168,000	20,485,000	26,463,000
General and Administrative Expense																	47,597,000	43,358,000	48,297,000
Costs and Expenses																	280,035,000	288,572,000	376,586,000
(Gain) loss on sale of assets																	(121,000)	54,000	44,060,000
Operating Income (Loss)	$ (14,278,000)		$ (16,667,000)		$ (31,318,000)		$ (26,481,000)		$ (27,484,000)		$ (14,445,000)	[3]	$ (21,510,000)		$ (780,000)	[3]	(88,744,000)	(64,219,000)	143,544,000
Gain on early extinguishment of debt																	15,478,000	0	0	$ (25,800,000)	$ (6,000,000)
Investment Income, Interest																	2,203,000	1,490,000	1,525,000
Interest Expense																	(51,364,000)	(48,675,000)	(39,496,000)
EquityinEarningsofConsolidatedSubsidiaries																	0	0	0
Other Nonoperating Income (Expense)																	(396,000)	2,052,000	1,005,000
Nonoperating Income (Expense)																	(34,079,000)	(45,133,000)	(36,966,000)
Income (Loss) before Income Taxes																	(122,823,000)	(109,352,000)	106,578,000
Income Tax Expense (benefit)																	(150,244,000)	(45,506,000)	39,757,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest																	27,421,000	(63,846,000)	66,821,000
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Revenues																		2,029,000	(1,301,000)
Operating Costs and Expenses																		1,971,000	(1,002,000)
Depreciation																		0	0
Amortization of Deferred Charges																		0	0
General and Administrative Expense																		58,000	(151,000)
Costs and Expenses																		2,029,000	(1,153,000)
(Gain) loss on sale of assets																		0	0
Operating Income (Loss)																		0	(148,000)
Investment Income, Interest																		0	0
Interest Expense																		0	0
EquityinEarningsofConsolidatedSubsidiaries																		14,989,000	(106,798,000)
Other Nonoperating Income (Expense)																		0	(180,000)
Nonoperating Income (Expense)																		14,989,000	(106,978,000)
Income (Loss) before Income Taxes																		14,989,000	(107,126,000)
Income Tax Expense (benefit)																		0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest																	(63,489,000)	14,989,000	(107,126,000)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Revenues																	0	0	0
Operating Costs and Expenses																	0	0	0
Depreciation																	0	0	0
Amortization of Deferred Charges																	0	0	0
General and Administrative Expense																	182,000	184,000	189,000
Costs and Expenses																	182,000	184,000	189,000
(Gain) loss on sale of assets																	0	0	0
Operating Income (Loss)																	(182,000)	(184,000)	(189,000)
Gain on early extinguishment of debt																	15,478,000
Investment Income, Interest																	0	0	0
Interest Expense																	(51,364,000)	(48,673,000)	(39,460,000)
EquityinEarningsofConsolidatedSubsidiaries																	63,489,000	(14,989,000)	106,798,000
Other Nonoperating Income (Expense)																	0	0	0
Nonoperating Income (Expense)																	27,603,000	(63,662,000)	67,338,000
Income (Loss) before Income Taxes																	27,421,000	(63,846,000)	67,149,000
Income Tax Expense (benefit)																	0	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest																	27,421,000	(63,846,000)	67,149,000
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues																	180,083,000	213,563,000	426,419,000
Operating Costs and Expenses																	108,517,000	114,783,000	178,748,000
Depreciation																	93,460,000	88,443,000	81,522,000
Amortization of Deferred Charges																	11,968,000	19,024,000	25,782,000
General and Administrative Expense																	45,078,000	39,479,000	44,398,000
Costs and Expenses																	259,023,000	261,729,000	330,450,000
(Gain) loss on sale of assets																	(133,000)	53,000	44,060,000
Operating Income (Loss)																	(79,073,000)	(48,113,000)	140,029,000
Gain on early extinguishment of debt																	0
Investment Income, Interest																	1,320,000	984,000	1,125,000
Interest Expense																	0	0	0
EquityinEarningsofConsolidatedSubsidiaries																	0	0	0
Other Nonoperating Income (Expense)																	1,157,000	(2,272,000)	(4,053,000)
Nonoperating Income (Expense)																	2,477,000	(1,288,000)	(2,928,000)
Income (Loss) before Income Taxes																	(76,596,000)	(49,401,000)	137,101,000
Income Tax Expense (benefit)																	(150,735,000)	(44,721,000)	35,194,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest																	74,139,000	(4,680,000)	101,907,000
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues																	11,694,000	8,707,000	50,952,000
Operating Costs and Expenses																	12,385,000	14,904,000	41,514,000
Depreciation																	5,273,000	4,628,000	1,044,000
Amortization of Deferred Charges																	1,200,000	1,461,000	681,000
General and Administrative Expense																	2,348,000	3,637,000	3,861,000
Costs and Expenses																	21,206,000	24,630,000	47,100,000
(Gain) loss on sale of assets																	12,000	1,000	0
Operating Income (Loss)																	(9,500,000)	(15,922,000)	3,852,000
Gain on early extinguishment of debt																	0
Investment Income, Interest																	883,000	506,000	400,000
Interest Expense																	0	(2,000)	(36,000)
EquityinEarningsofConsolidatedSubsidiaries																	0	0	0
Other Nonoperating Income (Expense)																	(1,542,000)	4,324,000	5,238,000
Nonoperating Income (Expense)																	(659,000)	4,828,000	5,602,000
Income (Loss) before Income Taxes																	(10,159,000)	(11,094,000)	9,454,000
Income Tax Expense (benefit)																	491,000	(785,000)	4,563,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest																	(10,650,000)	$ (10,309,000)	$ 4,891,000
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Revenues																	(365,000)
Operating Costs and Expenses																	(365,000)
Depreciation																	0
Amortization of Deferred Charges																	0
General and Administrative Expense																	(11,000)
Costs and Expenses																	(376,000)
(Gain) loss on sale of assets																	0
Operating Income (Loss)																	11,000
Gain on early extinguishment of debt																	0
Investment Income, Interest																	0
Interest Expense																	0
EquityinEarningsofConsolidatedSubsidiaries																	(63,489,000)
Other Nonoperating Income (Expense)																	(11,000)
Nonoperating Income (Expense)																	(63,500,000)
Income (Loss) before Income Taxes																	(63,489,000)
Income Tax Expense (benefit)																	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest																	$ (63,489,000)

[1] Results for the fiscal years 2017 and 2016 were significantly impacted by a drop in oil price, which resulted in reductions in both the Company's dayrates and utilization. In recognition of these weak market conditions, the Company elected to stack OSVs and MPSVs on various dates during fiscal 2017 and 2016. The Company had an average of 42.8 OSVs and 0.8 MPSVs stacked during the year ended December 31, 2017. The Company had an average of 41.3 OSVs and 0.3 MPSVs stacked during fiscal 2016.

[2] The sum of the four quarters may not equal annual results due to rounding.

[3] The results for the three months ended December 31, 2017 were favorably impacted by tax reform that was enacted in December 2017. As a result of tax reform, the Company recorded a benefit of $125,225 related to the repricing of its deferred tax liabilities. Such benefits were reduced primarily by tax expense related to credits that may not be utilized prior to their expiration. Excluding these one-time tax items from the Company's fourth quarter results its net loss would have been $(17,281) or $(0.47) per diluted share. See Note 9 for further information.