Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenues	$ 400,038	$ 264,086	$ 696,726	$ 488,035
Operating Income	33,046	11,184	45,149	15,904
Acquisition related costs	(139)	(262)	(612)	(262)
Heavy Civil
Segment Reporting Information [Line Items]
Revenues	220,448	200,236	376,063	350,741
Operating Income	3,896	5,747	274	3,600
Specialty Services
Segment Reporting Information [Line Items]
Revenues	135,703	27,894	240,426	58,573
Operating Income	23,246	865	34,360	1,913
Residential
Segment Reporting Information [Line Items]
Revenues	43,887	35,956	80,237	78,721
Operating Income	6,043	4,834	11,127	10,653
Operating Segments
Segment Reporting Information [Line Items]
Operating Income	$ 33,185	$ 11,446	$ 45,761	$ 16,166