Derivative Financial Instruments Derivative Instruments Not Designated as Hedges (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Effect of derivative instruments not designated as hedging instruments	$ (18,686,000)	$ (378,000)
Interest (expense)/income | Cross-currency swap agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Effect of derivative instruments not designated as hedging instruments	0	(554,000)
Other income/(loss), net | Cross-currency swap agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Effect of derivative instruments not designated as hedging instruments	0	176,000
Loss on settlement of foreign currency forward purchase contracts [Member] | British pound forward purchase contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Effect of derivative instruments not designated as hedging instruments	$ (18,686,000)	$ 0