Segment Information - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Contract revenues	$ 140,301	$ 86,091	$ 269,924	$ 167,546
Operating loss	281	(2,712)	(174)	(2,905)
Depreciation and amortization expense			(17,203)	(10,654)
Total Assets	443,334		443,334		$ 461,462
Property and equipment, net	164,384		164,384		$ 165,989
Operating Segments | Heavy Civil Marine Construction
Segment Reporting Information [Line Items]
Contract revenues	79,966	86,091	142,381	167,546
Operating loss	(1,212)	(2,712)	(4,354)	(2,905)
Depreciation and amortization expense	(5,176)	(5,209)	(10,243)	(10,654)
Total Assets	297,207	342,136	297,207	342,136
Property and equipment, net	149,912	158,642	149,912	158,642
Operating Segments | Commercial Concrete Construction
Segment Reporting Information [Line Items]
Contract revenues	60,335	0	127,543	0
Operating loss	1,493	0	4,180	0
Depreciation and amortization expense	(3,477)	0	(6,960)	0
Total Assets	146,127	0	146,127	0
Property and equipment, net	$ 14,472	$ 0	$ 14,472	$ 0