Supplemental Cash Flow Information - Net Effects of Changes in Operating Assets and Liabilities, Net, on Cash Flows from Operating Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Accounts and notes receivable	$ (159,469)	$ (131,712)
Contract assets	5,267	(6,184)
Inventories	28,996	(13,682)
Prepaid expenses and other current assets	(29,339)	(18,742)
Accounts payable and accrued expenses and other non-current liabilities	(66,678)	(27,211)
Contract liabilities	(23,380)	77,274
Other, net	(5,553)	2,663
Net change in operating assets and liabilities, net of non-cash transactions	$ (250,156)	$ (117,594)