Subsidiary Guarantors (Condensed Consolidated of Cash Flow) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
OPERATING ACTIVITIES:
Net income	$ 5,299	$ 4,566
Adjustments to reconcile net income to net cash flows used in operating activities:
Depreciation and amortization	16,123	18,804
Equity in loss of joint ventures	24	714
Loss on extinguishment of 7 3/4% senior subordinated notes		5,145
Deferred income taxes	(478)	1,010
Gain on dispositions of property and equipment	(124)	(2,771)
Amortization of deferred financing fees	669	775
Unrealized foreign currency gain	378
Share-based compensation expense	1,714	843
Excess income tax benefit from share based compensation	(118)	(52)
Changes in assets and liabilities:
Accounts receivable	4,301	(13,025)
Inventories	(8,653)	(362)
Prepaid expenses and other current assets	(5,873)	(12,432)
Accounts payable and accrued expenses	(11,771)	(5,523)
Net cash flows used in operating activities	(15,185)	(10,445)
INVESTING ACTIVITIES:
Purchases of property and equipment	(22,428)	(13,583)
Proceeds from dispositions of property and equipment	226	7,275
Net cash flows used in investing activities	(22,202)	(6,308)
FINANCING ACTIVITIES:
Proceeds from issuance of 7 3/8% senior notes		250,000
Redemption of 7 3/4% senior subordinated notes		(175,000)
Senior subordinated notes redemption premium		(2,264)
Deferred financing fees	(2,039)	(5,829)
Distribution made to member or limited partner, cash distributions paid	(133)
Dividends paid	(2,482)	(2,236)
Dividend equivalents paid on restricted stock units	(22)	(11)
Taxes paid on settlement of vested share awards	(212)	(250)
Repayments of equipment debt	(426)	(217)
Exercise of stock options	75	27
Excess income tax benefit from share-based compensation	118	52
Net cash flows provided by (used in) financing activities	(5,121)	64,272
Effect of foreign currency exchange rates on cash and cash equivalents	11
Net increase (decrease) in cash and cash equivalents	(42,497)	47,519
Cash and cash equivalents at beginning of period	113,288	48,478
Cash and cash equivalents at end of period	70,791	95,997
Supplemental Cash Flow Information
Cash paid for interest	9,602	2,728
Cash paid (refunded) for income taxes	(6,371)	5,155
Non-cash Investing and Financing Activities
Property and equipment purchased but not yet paid	6,231	4,303
Acquisition of noncontrolling interest in NASDI, LLC		40
GLDD Corporation [Member]
OPERATING ACTIVITIES:
Net income	5,299	4,566
Adjustments to reconcile net income to net cash flows used in operating activities:
Loss on extinguishment of 7 3/4% senior subordinated notes		5,145
Changes in assets and liabilities:
Net cash flows used in operating activities	(25,028)	(16,679)
FINANCING ACTIVITIES:
Proceeds from issuance of 7 3/8% senior notes		250,000
Redemption of 7 3/4% senior subordinated notes		(175,000)
Senior subordinated notes redemption premium		(2,264)
Deferred financing fees	(2,039)	(5,829)
Distribution made to member or limited partner, cash distributions paid	(133)
Dividends paid	(2,482)	(2,236)
Dividend equivalents paid on restricted stock units	(22)	(11)
Taxes paid on settlement of vested share awards	(212)	(250)
Net change in account with affiliate	(29,723)	47,810
Exercise of stock options	75	27
Excess income tax benefit from share-based compensation	118	52
Net cash flows provided by (used in) financing activities	25,028	16,679
Subsidiary Guarantors [Member]
OPERATING ACTIVITIES:
Net income	19,012	28,118
Adjustments to reconcile net income to net cash flows used in operating activities:
Equity in loss of joint ventures	24	714
Changes in assets and liabilities:
Net cash flows used in operating activities	9,512	3,004
INVESTING ACTIVITIES:
Purchases of property and equipment	(22,428)	(13,583)
Proceeds from dispositions of property and equipment	226	7,275
Net cash flows used in investing activities	(22,202)	(6,308)
FINANCING ACTIVITIES:
Net change in account with affiliate	25,246	(50,703)
Repayments of equipment debt	(426)	(217)
Net cash flows provided by (used in) financing activities	(25,672)	50,486
Net increase (decrease) in cash and cash equivalents	(38,362)	47,182
Cash and cash equivalents at beginning of period	108,985	48,416
Cash and cash equivalents at end of period	70,623	95,598
Non-Guarantor Subsidiaries [Member]
OPERATING ACTIVITIES:
Net income	(917)	1,214
Changes in assets and liabilities:
Net cash flows used in operating activities	331	3,230
FINANCING ACTIVITIES:
Net change in account with affiliate	4,477	2,893
Net cash flows provided by (used in) financing activities	(4,477)	(2,893)
Effect of foreign currency exchange rates on cash and cash equivalents	11
Net increase (decrease) in cash and cash equivalents	(4,135)	337
Cash and cash equivalents at beginning of period	4,303	62
Cash and cash equivalents at end of period	168	399
Eliminations [Member]
OPERATING ACTIVITIES:
Net income	$ (18,095)	$ (29,332)