Segment Information - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Contract revenues	$ 140,162	$ 164,017	$ 416,339	$ 433,941
Operating loss	(5,354)	9,531	(9,302)	9,357
Depreciation and amortization expense			(22,422)	(25,765)
Total Assets	426,706		426,706		$ 447,676
Property and equipment, net	148,779		148,779		$ 158,082
Operating Segments | Marine Construction
Segment Reporting Information [Line Items]
Contract revenues	68,383	82,169	197,566	224,550
Operating loss	(9,837)	3,272	(26,160)	(1,082)
Depreciation and amortization expense	(5,075)	(5,547)	(15,417)	(15,790)
Total Assets	248,960	306,788	248,960	306,788
Property and equipment, net	131,630	146,361	131,630	146,361
Operating Segments | Concrete Construction
Segment Reporting Information [Line Items]
Contract revenues	71,779	81,848	218,773	209,391
Operating loss	4,483	6,259	16,858	10,439
Depreciation and amortization expense	(2,229)	(3,015)	(7,005)	(9,975)
Total Assets	177,746	161,419	177,746	161,419
Property and equipment, net	$ 17,149	$ 14,882	$ 17,149	$ 14,882