Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
CONTRACT REVENUES	$ 620,795	$ 592,159	$ 637,468
Type of Revenue [Extensible List]	gldd:ContractMember	gldd:ContractMember	gldd:ContractMember
COSTS OF CONTRACT REVENUES	$ 509,335	$ 549,429	$ 552,130
Type of Cost, Good or Service [Extensible List]	gldd:ContractMember	gldd:ContractMember	gldd:ContractMember
GROSS PROFIT	$ 111,460	$ 42,730	$ 85,338
OPERATING EXPENSES:
GENERAL AND ADMINISTRATIVE EXPENSES	55,108	57,235	55,271
LOSS ON SALE OF ASSETS—Net	3,731	4,789	3,089
Total operating income (loss)	52,621	(19,294)	26,978
OTHER EXPENSE:
Interest expense—net	(33,578)	(26,032)	(23,471)
Equity in loss of joint ventures		(1,484)	(2,365)
Loss on extinguishment of debt		(2,330)
Other income (expense)	(2,590)	11	(777)
Total other expense	(36,168)	(29,835)	(26,613)
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	16,453	(49,129)	365
INCOME TAX (PROVISION) BENEFIT	(5,437)	33,761	177
INCOME (LOSS) FROM CONTINUING OPERATIONS	11,016	(15,368)	542
Loss from discontinued operations, net of income taxes	(17,309)	(15,892)	(8,719)
NET LOSS	$ (6,293)	$ (31,260)	$ (8,177)
Basic earnings (loss) per share attributable to income (loss) from continuing operations	$ 0.18	$ (0.25)	$ 0.01
Basic loss per share attributable to loss on discontinued operations, net of income taxes	(0.28)	(0.26)	(0.14)
Basic loss per share	$ (0.10)	$ (0.51)	$ (0.13)
Basic weighted average shares	62,236	61,365	60,744
Diluted earnings (loss) per share attributable to income (loss) from continuing operations	$ 0.17	$ (0.25)	$ 0.01
Diluted loss per share attributable to loss on discontinued operations, net of income taxes	(0.27)	(0.26)	(0.14)
Diluted loss per share	$ (0.10)	$ (0.51)	$ (0.13)
Diluted weighted average shares	63,607	61,365	61,367