Construction Contracts - Net Position of Uncompleted Construction Contracts (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Contractors [Abstract]
Costs incurred on uncompleted construction contracts	$ 333,744	$ 228,184
Estimated earnings	10,936	9,739
Billings	(354,737)	(240,059)
Construction contract costs and estimated earnings in excess of billings	110	88
Billings in excess of construction contract costs and estimated earnings	(10,167)	(2,224)
Net position	$ (10,057)	$ (2,136)