Derivative Financial Instruments Derivative Instruments Not Designated as Hedges (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Effect of derivative instruments not designated as hedging instruments	$ 0	$ (892,000)	$ (18,686,000)	$ (1,270,000)
Not Designated as Hedging Instrument [Member] | Interest expense [Member] | Cross-currency swap agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Effect of derivative instruments not designated as hedging instruments	0	(630,000)	0	(1,184,000)
Not Designated as Hedging Instrument [Member] | Other income, net [Member] | Cross-currency swap agreements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Effect of derivative instruments not designated as hedging instruments	0	(262,000)	0	(86,000)
Not Designated as Hedging Instrument [Member] | 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	$ 0	$ 0	$ (18,686,000)	$ 0