Segment Information - Summary (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Contract revenues	$ 136,843	$ 138,757
Operating income (loss)	7,069	(1,482)
Depreciation and amortization expense	(6,780)	(7,528)
Total Assets	422,433		$ 433,285
Property and equipment, net	144,868		$ 146,278
Marine
Segment Reporting Information [Line Items]
Contract revenues	62,791
Concrete
Segment Reporting Information [Line Items]
Contract revenues	74,052
Intersegment Eliminations
Segment Reporting Information [Line Items]
Contract revenues	100
Operating Segments | Marine
Segment Reporting Information [Line Items]
Contract revenues	62,791	67,180
Operating income (loss)	6,265	(7,707)
Depreciation and amortization expense	(4,731)	(5,255)
Total Assets	255,484	261,176
Property and equipment, net	127,078	139,221
Operating Segments | Concrete
Segment Reporting Information [Line Items]
Contract revenues	74,052	71,577
Operating income (loss)	804	6,225
Depreciation and amortization expense	(2,049)	(2,273)
Total Assets	166,949	170,262
Property and equipment, net	$ 17,790	$ 14,695