Segment Information - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Contract revenues	$ 125,073	$ 140,162	$ 421,682	$ 416,339
Operating (loss) income	(7,405)	(5,354)	4,254	(9,302)
Depreciation and amortization expense			(21,134)	(22,422)
Total Assets	424,748		424,748		$ 433,285
Property and equipment, net	144,387		144,387		$ 146,278
Marine
Segment Reporting Information [Line Items]
Contract revenues	63,479		206,967
Concrete
Segment Reporting Information [Line Items]
Contract revenues	61,594		214,715
Intersegment Eliminations
Segment Reporting Information [Line Items]
Contract revenues	100		2,400
Operating Segments | Marine
Segment Reporting Information [Line Items]
Contract revenues	63,479	68,383	206,967	197,566
Operating (loss) income	(5,559)	(9,837)	4,348	(26,160)
Depreciation and amortization expense	(4,746)	(5,075)	(14,772)	(15,417)
Total Assets	269,501	248,960	269,501	248,960
Property and equipment, net	125,231	131,630	125,231	131,630
Operating Segments | Concrete
Segment Reporting Information [Line Items]
Contract revenues	61,594	71,779	214,715	218,773
Operating (loss) income	(1,846)	4,483	(94)	16,858
Depreciation and amortization expense	(2,176)	(2,229)	(6,362)	(7,005)
Total Assets	155,247	177,746	155,247	177,746
Property and equipment, net	$ 19,156	$ 17,149	$ 19,156	$ 17,149