Earnings Per Share - (Schedule of Stock Options and Restricted Stock Units Excluded from Diluted Weighted-Average Common Shares) (Details) shares in Thousands	12 Months Ended
Dec. 31, 2017 shares
Earnings Per Share [Abstract]
Effect of stock options and restricted stock units	716

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