Contracts in Progress (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Contractors [Abstract]
Costs incurred on uncompleted contracts	$ 872,607	$ 782,934
Estimated earnings	167,697	132,694
Costs incurred and estimated earnings on uncompleted contracts	1,040,304	915,628
Less: Billings to date	(1,017,152)	(884,504)
Costs and estimated earnings in excess of billings on uncompleted contracts, net	23,152	31,124
Costs and estimated earnings in excess of billings on uncompleted contracts	52,720	59,608
Billings in excess of costs and estimated earnings on uncompleted contracts	(29,568)	(28,484)
Costs and estimated earnings in excess of billings on completed contracts, net of billings (totaled less than)	$ 500	$ 600