Earnings Per Share - (Schedule of Stock Options and Restricted Stock Units Excluded from Diluted Weighted-Average Common Shares) (Details) - shares shares in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2018
Earnings Per Share [Abstract]
Effect of stock options and restricted stock units	429	920

Securities excluded from computation of earnings per share amount due to loss.

No definition available.

Name:	gldd_SecuritiesExcludedFromComputationOfEarningsPerShareAmountDueToLoss
Namespace Prefix:	gldd_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration