Contract Assets and Liabilities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Loss Contingencies [Line Items]
Revenue recognized	$ 89,300
Construction	269,243	$ 226,849
Aggregate claim recovery estimate included in contract assets and liability	34,000		$ 26,700
Costs in excess of billings and estimated earnings and billings in excess of estimated earnings		$ 12,500
Performance Obligations
Loss Contingencies [Line Items]
Construction	$ 27,700