Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Amounts reclassified from AOCI
Foreign currency derivatives gains, net	$ (543,315)	$ (497,243)	$ (1,464,715)	$ (1,326,306)
Interest rate derivative losses, net	13,479	11,975	37,019	31,745
Total before tax	(67,418)	(73,803)	(58,254)	(91,971)
Income tax expense (benefit)	26,814	28,320	23,479	35,326
Total net of tax	(40,604)	(45,483)	(34,775)	(56,645)
Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Total net of tax	(382)		(382)
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Total before tax	(2,788)		(5,955)
Income tax expense (benefit)	1,025		2,226
Total net of tax	(1,763)		(3,729)
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss | Foreign currency derivatives gains
Amounts reclassified from AOCI
Foreign currency derivatives gains, net	(3,005)		(6,395)
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	217		440
Defined benefit pension | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Actuarial loss	2,281		6,384
Prior service credit	(1)		(3)
Total before tax	2,280		6,381
Income tax expense (benefit)	(899)		(3,034)
Total net of tax	$ 1,381		$ 3,347