Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Amounts reclassified from AOCI
Foreign currency derivative gains, net	$ (566,985)	$ (543,315)	$ (1,541,795)	$ (1,464,715)
Interest rate derivative losses, net	17,104	13,479	48,111	37,019
Total before tax	(58,364)	(67,418)	(95,051)	(58,254)
Tax expense (benefit)	22,789	26,814	37,224	23,479
Total, net of tax	(35,575)	(40,604)	(57,827)	(34,775)
Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Total, net of tax	(637)	(382)	(3,393)	(382)
Gains on derivatives designated as hedging instruments | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Total before tax	(1,096)	(2,788)	(5,905)	(5,955)
Tax expense (benefit)	424	1,025	2,239	2,226
Total, net of tax	(672)	(1,763)	(3,666)	(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 derivative gains, net	(1,297)	(3,005)	(6,523)	(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	201	217	618	440
Defined benefit pension | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Actuarial loss (gain)	(64)	2,281	388	6,384
Prior service cost (credit)	113	(1)	111	(3)
Total before tax	49	2,280	499	6,381
Tax expense (benefit)	(5)	(899)	(215)	(3,034)
Total, net of tax	44	1,381	284	3,347
Short-term investments | Amount reclassified from accumulated other comprehensive loss
Amounts reclassified from AOCI
Realized gain on sales of investments, net	(10)	0	(12)	0
Total before tax	(10)	0	(12)	0
Tax expense (benefit)	1	0	1	0
Total, net of tax	$ (9)	$ 0	$ (11)	$ 0