CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Loss	$ (213,512)	$ (533,299)	$ (1,054,579)
Other Comprehensive (Loss) Income, Net of Tax
Currency translation adjustments	18,919	(106,651)	191,267
Defined benefit pension plan adjustments	(27,094)	450	14,491
Net unrealized losses on available-for-sale security	(1,713)	(3,748)	(5,948)
Net unrealized (losses) gains on derivative instruments:
Unrealized holding gains (losses)	17,024
Amounts reclassified from accumulated other comprehensive loss	(17,394)
Net unrealized gains (losses) on derivative instruments	(370)
Unrealized holding gains (losses)		24,082	(55,377)
Amounts reclassified from accumulated other comprehensive loss		8,427	16,810
Net unrealized gains (losses) on derivative instruments		32,509	(38,567)
Other Comprehensive (Loss) Income, Net of Tax	(10,258)	(77,440)	161,243
Comprehensive Loss	$ (223,770)	$ (610,739)	$ (893,336)