Summary of Significant Accounting Policies - Schedule of costs and estimated earnings on uncompleted contracts and related amounts billed (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Costs incurred on uncompleted contracts	$ 7,582,108	$ 7,620,522
Estimated earnings, thereon	862,987	808,549
Costs and estimated earnings on uncompleted contracts	8,445,095	8,429,071
Less: billings to date	8,756,596	8,694,425
Net billings in excess of costs	(311,501)	(265,354)
Costs and estimated earnings in excess of billings on uncompleted contracts	117,734	103,201	$ 90,727
Billings in excess of costs and estimated earnings on uncompleted contracts	$ (429,235)	$ (368,555)	$ (381,295)