Supplemental Cash Flow Information - Net Effect of Changes in Operating Assets and Liabilities, Net of Non-Cash Transactions, on Cash Flows from Operating Activities of Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Accounts and notes receivable	$ (475,919)	$ (425,313)	$ 144,877
Contract assets	(92,838)	15,999	(152,702)
Inventories	(28,131)	14,110	(9,905)
Prepaid expenses and other current assets	(40,187)	(32,079)	25,133
Accounts payable and accrued expenses and other non-current liabilities	247,897	28,547	81,246
Contract liabilities	(23)	139,114	(124,680)
Other, net	(11,332)	17,858	(12,635)
Net change in operating assets and liabilities, net of non-cash transactions	$ (400,533)	$ (241,764)	$ (48,666)