Accumulated Other Comprehensive Loss - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Amounts reclassified from AOCI
Foreign currency derivative gains, net	$ 499,387	$ 506,797	$ 968,532	$ 974,810
Interest rate derivative losses, net	(13,718)	(15,997)	(29,236)	(31,007)
Income Before Income Taxes	79,261	44,979	121,260	36,687
Tax expense (benefit)	(30,427)	(17,652)	(46,543)	(14,435)
Net Income	48,834	27,327	74,717	22,252
Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Net Income	(983)	(736)	(1,636)	(2,756)
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Income Before Income Taxes	(4,281)	(1,402)	(8,046)	(4,809)
Tax expense (benefit)	1,618	527	3,040	1,815
Net Income	(2,663)	(875)	(5,006)	(2,994)
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss | Foreign currency derivatives gains
Amounts reclassified from AOCI
Foreign currency derivative gains, net	(4,460)	(1,608)	(8,412)	(5,226)
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss | Interest rate derivatives loss
Amounts reclassified from AOCI
Interest rate derivative losses, net	179	206	366	417
Defined benefit pension | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Actuarial loss	2,680	226	5,360	452
Prior service cost (credit)	57	(1)	114	(2)
Income Before Income Taxes	2,737	225	5,474	450
Tax expense (benefit)	(1,038)	(85)	(2,076)	(210)
Net Income	1,699	140	3,398	240
Short-Term Investments | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Realized gain on sales of investments, net	(25)	(1)	(35)	(2)
Income Before Income Taxes	(25)	(1)	(35)	(2)
Tax expense (benefit)	6	0	7	0
Net Income	$ (19)	$ (1)	$ (28)	$ (2)