Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Amounts reclassified from AOCI
Foreign currency derivative gains, net	$ (506,797)	$ (481,461)	$ (974,810)	$ (921,400)
Interest expense and amortization of debt discounts and issuance costs	(15,997)	(12,163)	(31,007)	(23,540)
Total before tax	(44,979)	(18,215)	(36,687)	9,164
Income tax expense (benefit)	17,652	6,899	14,435	(3,335)
Total net of tax	(27,327)	(11,316)	(22,252)	5,829
Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Total before tax	(1,402)	(2,900)	(4,809)	(3,167)
Income tax expense (benefit)	527	1,095	1,815	1,201
Total net of tax	(736)	(1,078)	(2,756)	0
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Total net of tax	(875)	(1,805)	(2,994)	(1,966)
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	(1,608)	(3,123)	(5,226)	(3,390)
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss | Interest rate derivatives loss
Amounts reclassified from AOCI
Interest expense and amortization of debt discounts and issuance costs	(206)	(223)	(417)	(223)
Defined benefit pension | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Actuarial loss	226	2,051	452	4,103
Prior service credit	(1)	(1)	(2)	(2)
Total before tax	225	2,050	450	4,101
Income tax expense (benefit)	(85)	(1,323)	(210)	(2,135)
Total net of tax	140	727	240	1,966
Short-term investments | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Realized gain on sales of investments, net	(1)		(2)
Total before tax	(1)		(2)
Total net of tax	$ (1)		$ (2)