Consolidated Statements of Cash Flows (Changes in Other Components of Working Capital) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Consolidated Statement of Cash Flows [Abstract]
Accounts receivable	$ 3,899	$ (91,062)	$ (184,549)
Retainage receivable	56,754	33,453	(85,351)
Costs and estimated earnings in excess of billings	(209,537)	(100,932)	73,349
Other current assets	15,398	(19,718)	39,480
Accounts payable	(78,243)	(35,751)	3,025
Retainage payable	(49,864)	3,526	53,527
Billings in excess of costs and estimated earnings	76,703	125,757	42,926
Accrued expenses and other current liabilities	28,046	24,513	(32,937)
Changes in other components of working capital	(156,844)	(60,214)	(90,530)
Interest	51,063	50,443	47,403
Income taxes	$ 13,652	$ 39,776	$ 26,908