Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments (segment) | segment	2	2
Contract revenues	$ 143,105	$ 136,843
Marine
Segment Reporting Information [Line Items]
Contract revenues	61,487	62,791
Marine | Mexico and the Caribbean
Segment Reporting Information [Line Items]
Contract revenues		500	$ 6,000
Concrete
Segment Reporting Information [Line Items]
Contract revenues	$ 81,618	74,052
Intersegment Eliminations
Segment Reporting Information [Line Items]
Contract revenues		$ 100