Summary of Significant Accounting Policies - Insurance Coverage (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) levels policy	Dec. 31, 2015 USD ($)
Insurance Coverage [Line Items]
Levels of insurance coverage maintained by the Company | levels	5
Number of Insurance Policies | policy	2
Accrual for self-insurance liabilities	$ 5,223,000	$ 7,998,000
Heavy Civil Marine Construction Segment
Insurance Coverage [Line Items]
Levels of insurance coverage maintained by the Company | levels	5
Amount in excess of primary insurance coverage	$ 200,000,000
Heavy Civil Marine Construction Segment | Other liability policies
Insurance Coverage [Line Items]
Primary limit of insurance coverage	1,000,000
Heavy Civil Marine Construction Segment | Maritime employer's liability
Insurance Coverage [Line Items]
Primary limit of insurance coverage	10,000,000
Heavy Civil Marine Construction Segment | Watercraft pollution policy
Insurance Coverage [Line Items]
Primary limit of insurance coverage	$ 5,000,000
Commercial Concrete Segment
Insurance Coverage [Line Items]
Levels of insurance coverage maintained by the Company | levels	2
Amount in excess of primary insurance coverage	$ 200,000,000
Commercial Concrete Segment | Other liability policies
Insurance Coverage [Line Items]
Primary limit of insurance coverage	$ 1,000,000