Goodwill and Intangible Assets Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 69,483	$ 66,351		$ 65,982
Heavy Civil Marine Construction Segment
Goodwill [Line Items]
Goodwill	33,800
Commercial Concrete Segment
Goodwill [Line Items]
Goodwill	$ 35,700
Estimate of Fair Value Measurement | Heavy Civil Marine Construction Segment
Goodwill [Line Items]
Goodwill impairment, segment value			$ 212,000
Estimate of Fair Value Measurement | Commercial Concrete Segment
Goodwill [Line Items]
Goodwill impairment, segment value			153,000
Reported Value Measurement | Heavy Civil Marine Construction Segment
Goodwill [Line Items]
Goodwill impairment, segment value			188,000
Reported Value Measurement | Commercial Concrete Segment
Goodwill [Line Items]
Goodwill impairment, segment value			$ 134,500