Consolidated Statements of Cash Flows (Changes in Other Components of Working Capital) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statement of Cash Flows [Abstract]
Accounts receivable	$ (81,983)	$ 3,899	$ (91,062)
Retainage receivable	(78,520)	56,754	33,453
Costs and estimated earnings in excess of billings	18,751	(209,537)	(100,932)
Other current assets	(76,146)	15,398	(19,718)
Accounts payable	53,999	(78,243)	(35,751)
Retainage payable	35,013	(49,864)	3,526
Billings in excess of costs and estimated earnings	245,292	76,703	125,757
Accrued expenses and other current liabilities	14,851	28,046	24,513
Changes in other components of working capital	131,257	(156,844)	(60,214)
Interest	56,137	51,063	50,443
Income taxes	$ 43,374	$ 13,652	$ 39,776