CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Loss	$ (240,931)	$ (56,075)	$ (552,184)	$ (169,306)
Other Comprehensive Income (Loss), Net of Tax:
Currency translation adjustments	(105,727)	51,067	(63,738)	105,336
Defined benefit pension plan adjustments	1,069	1,024	2,685	2,079
Net unrealized losses on available-for-sale security	(2,709)	(2,423)	(2,789)	(3,737)
Net unrealized gains (losses) on derivative instruments:
Unrealized holding gains (losses)	17,652	(27,406)	12,333	(39,990)
Reclassification adjustment for realized losses (gains) included in net loss	4,786	(364)	9,217	(2,593)
Net unrealized gains (losses) on derivative instruments	22,438	(27,770)	21,550	(42,583)
Other Comprehensive (Loss) Income, Net of Tax	(84,929)	21,898	(42,292)	61,095
Comprehensive Loss	$ (325,860)	$ (34,177)	$ (594,476)	$ (108,211)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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