CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 6,278	$ (603,247)	$ (545,906)	$ (772,553)
Other Comprehensive (Loss) Income, Net of Tax
Currency translation adjustments	(17,132)	36,912	(80,870)	142,248
Defined benefit pension plan adjustments	1,762	1,106	4,447	3,185
Net unrealized gains (losses) on available-for-sale security	424	(3,848)	(2,365)	(7,585)
Net unrealized gains (losses) on derivative instruments:
Unrealized holding gains (losses)	3,215	(24,009)	15,548	(63,999)
Reclassification adjustment for realized gains included in net income (loss)	787	9,241	10,004	6,648
Net unrealized gains (losses) on derivative instruments	4,002	(14,768)	25,552	(57,351)
Other Comprehensive (Loss) Income, Net of Tax	(10,944)	19,402	(53,236)	80,497
Comprehensive Loss	$ (4,666)	$ (583,845)	$ (599,142)	$ (692,056)

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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