Consolidated Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statement of Cash Flows [Abstract]
Accounts receivable	$ (269,900)	$ 4,734	$ (186,384)
Costs and estimated earnings in excess of billings	73,349	(178,774)	(153,153)
Other current assets	39,480	(38,616)	(17,450)
Accounts payable	56,552	139,290	33,667
Billings in excess of costs and estimated earnings	42,926	(30,985)	51,711
Accrued expenses	(32,937)	(24,426)	2,801
Changes in other components of working capital	(90,530)	(128,777)	(268,808)
Interest	47,403	45,055	45,236
Income taxes	$ 26,908	$ 35,299	75,494
Property and equipment acquired through financing arrangements not included in cash flows from financing activities			$ 816