Subsidiary Guarantors (Condensed Consolidated Statement Operations And Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Contract revenues	$ 166,532	$ 154,959	$ 321,439	$ 310,297
Costs of contract revenues	(142,643)	(135,193)	(277,528)	(263,089)
Gross profit	23,889	19,766	43,911	47,208
General and administrative expenses	11,456	13,622	24,723	25,711
Gain on sale of assets-net	(93)	(2,513)	(124)	(2,771)
Operating income	12,526	8,657	19,312	24,268
Interest expense-net	(5,383)	(4,911)	(10,642)	(10,861)
Equity in loss of joint ventures	(8)	(123)	(24)	(714)
Loss on foreign currency transactions-net	(21)		(15)
Loss on extinguishment of debt				(5,145)
Income before income taxes	7,114	3,623	8,631	7,548
Income tax (provision) benefits	(2,768)	(1,455)	(3,332)	(2,982)
Net income	4,346	2,168	5,299	4,566
Net loss attributable to noncontrolling interests	91	(462)	206	(468)
Net income attributable to Great Lakes Dredge & Dock Corporation	4,437	1,706	5,505	4,098
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	2,667	892	4,213
GLDD Corporation [Member]
General and administrative expenses	615	892	1,127	1,564
Gain on sale of assets-net			11
Operating income	(615)	(892)	(1,138)	(1,564)
Interest expense-net	(5,103)	(4,808)	(10,053)	(10,633)
Equity in earnings (loss) of subsidiaries	12,350	11,567	18,697	28,118
Loss on extinguishment of debt				(5,145)
Income before income taxes	6,632	5,867	7,506	10,776
Income tax (provision) benefits	(2,286)	(3,699)	(2,207)	(6,210)
Net income	4,346	2,168	5,299	4,566
Net loss attributable to noncontrolling interests	91	(462)	206	(468)
Net income attributable to Great Lakes Dredge & Dock Corporation	4,437	1,706	5,505	4,098
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	2,667	892	4,213
Subsidiary Guarantors [Member]
Contract revenues	166,467	151,223	321,911	305,262
Costs of contract revenues	(142,315)	(132,879)	(277,482)	(259,788)
Gross profit	24,152	18,344	44,429	45,474
General and administrative expenses	10,679	12,522	23,248	23,726
Gain on sale of assets-net	(93)	(2,513)	(135)	(2,771)
Operating income	13,566	8,335	21,316	24,519
Interest expense-net	(257)	(49)	(538)	(129)
Equity in earnings (loss) of subsidiaries	(223)	1,160	(602)	1,214
Equity in loss of joint ventures	(8)	(123)	(24)	(714)
Loss on foreign currency transactions-net	(21)		(15)
Income before income taxes	13,057	9,323	20,137	24,890
Income tax (provision) benefits	(482)	2,244	(1,125)	3,228
Net income	12,575	11,567	19,012	28,118
Net income attributable to Great Lakes Dredge & Dock Corporation	12,575	11,567	19,012	28,118
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	10,813	10,753	17,724
Non-Guarantor Subsidiaries [Member]
Contract revenues	2,251	6,269	4,050	9,586
Costs of contract revenues	(2,514)	(4,847)	(4,568)	(7,852)
Gross profit	(263)	1,422	(518)	1,734
General and administrative expenses	162	208	348	421
Operating income	(425)	1,214	(866)	1,313
Interest expense-net	(23)	(54)	(51)	(99)
Income before income taxes	(448)	1,160	(917)	1,214
Net income	(448)	1,160	(917)	1,214
Net income attributable to Great Lakes Dredge & Dock Corporation	(448)	1,160	(917)	1,214
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	(456)	1,160	(921)
Eliminations [Member]
Contract revenues	(2,186)	(2,533)	(4,522)	(4,551)
Costs of contract revenues	2,186	2,533	4,522	4,551
Equity in earnings (loss) of subsidiaries	(12,127)	(12,727)	(18,095)	(29,332)
Income before income taxes	(12,127)	(12,727)	(18,095)	(29,332)
Net income	(12,127)	(12,727)	(18,095)	(29,332)
Net income attributable to Great Lakes Dredge & Dock Corporation	(12,127)	(12,727)	(18,095)	(29,332)
Comprehensive income (loss) attributable to Great Lakes Dredge & Dock Corporation	$ (10,357)	$ (11,913)	$ (16,803)