Segment Information (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)	Dec. 31, 2015 segment
Segment Reporting Information [Line Items]
Number of reportable segments (segment) | segment			2		1
Contract revenues	$ 140,301,000	$ 86,091,000	$ 269,924,000	$ 167,546,000
Heavy Civil Marine Construction | Mexico and the Caribbean
Segment Reporting Information [Line Items]
Contract revenues	3,700,000	11,300,000	6,100,000	18,500,000
Intersegment Eliminations
Segment Reporting Information [Line Items]
Contract revenues	$ 0	$ 0	$ 0	$ 0