Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments (segment) | segment	2
Contract revenues	$ 136,843	$ 138,757
Marine
Segment Reporting Information [Line Items]
Contract revenues	62,791
Marine | Mexico and the Caribbean
Segment Reporting Information [Line Items]
Contract revenues	6,000	$ 100
Concrete
Segment Reporting Information [Line Items]
Contract revenues	74,052
Intersegment Eliminations
Segment Reporting Information [Line Items]
Contract revenues	$ 100