Subsidiary Guarantors (Condensed Consolidated of Cash Flow) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	$ 12,978	$ (3,897)
INVESTING ACTIVITIES:
Purchases of property and equipment	(58,842)	(53,394)
Proceeds from dispositions of property and equipment	10,455	1,167
Net cash flows used in investing activities	(48,387)	(52,227)
FINANCING ACTIVITIES:
Deferred financing fees	(332)	(29)
Repayments of long term note payable	(803)	(488)
Taxes paid on settlement of vested share awards	(162)	(265)
Repayments of term loan facility	(3,750)	(3,750)
Repayments of equipment debt	(1,064)	(853)
Proceeds from equipment debt		410
Exercise of options and purchases from employee stock plans	905	1,356
Excess income tax benefit from share-based compensation		(13)
Treasury stock		(1,107)
Borrowings under revolving loans	133,000	146,000
Repayments of revolving loans	(93,000)	(118,000)
Net cash provided by financing activities	34,794	23,261
Effect of foreign currency exchange rates on cash and cash equivalents	26	(105)
Net decrease in cash and cash equivalents	(589)	(32,968)
Cash and cash equivalents at beginning of period	14,184	42,389
Cash and cash equivalents at end of period	13,595	9,421
Consolidation Eliminations [Member]
INVESTING ACTIVITIES:
Net change in accounts with affiliates	(10,505)	38,898
Net cash flows used in investing activities	(10,505)	38,898
FINANCING ACTIVITIES:
Net change in accounts with affiliates	10,505	(38,898)
Net cash provided by financing activities	10,505	(38,898)
Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	36,242	15,013
INVESTING ACTIVITIES:
Purchases of property and equipment	(58,842)	(53,394)
Proceeds from dispositions of property and equipment	10,455	1,167
Net change in accounts with affiliates	10,505	(29,059)
Net cash flows used in investing activities	(37,882)	(81,286)
FINANCING ACTIVITIES:
Repayments of equipment debt	(1,064)	(853)
Net change in accounts with affiliates	26,733	17,416
Capital contributions		16,800
Intercompany dividends	(23,000)
Net cash provided by financing activities	2,669	33,363
Net decrease in cash and cash equivalents	1,029	(32,910)
Cash and cash equivalents at beginning of period	12,035	41,724
Cash and cash equivalents at end of period	13,064	8,814
Non Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	(3,096)	(1,308)
FINANCING ACTIVITIES:
Net change in accounts with affiliates	1,452	1,355
Net cash provided by financing activities	1,452	1,355
Effect of foreign currency exchange rates on cash and cash equivalents	26	(105)
Net decrease in cash and cash equivalents	(1,618)	(58)
Cash and cash equivalents at beginning of period	2,147	663
Cash and cash equivalents at end of period	529	605
GLDD Corporation [Member]
OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	(20,168)	(17,602)
INVESTING ACTIVITIES:
Net change in accounts with affiliates		(9,839)
Net cash flows used in investing activities		(9,839)
FINANCING ACTIVITIES:
Deferred financing fees	(332)	(29)
Repayments of long term note payable	(803)	(488)
Taxes paid on settlement of vested share awards	(162)	(265)
Repayments of term loan facility	(3,750)	(3,750)
Proceeds from equipment debt		410
Net change in accounts with affiliates	(38,690)	20,127
Capital contributions		(16,800)
Intercompany dividends	23,000
Exercise of options and purchases from employee stock plans	905	1,356
Excess income tax benefit from share-based compensation		(13)
Treasury stock		(1,107)
Borrowings under revolving loans	133,000	146,000
Repayments of revolving loans	(93,000)	(118,000)
Net cash provided by financing activities	20,168	27,441
Cash and cash equivalents at beginning of period	2	2
Cash and cash equivalents at end of period	$ 2	$ 2