Derivative Financial Instruments Derivative Instruments Designated as Cash Flow Hedges OCI Activity (Details) - Other Comprehensive Income (Loss) [Member] - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (4,253)	$ (1,454)	$ (7,857)	$ (14,873)
Interest rate swap agreements [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(8,734)	(1,454)	(7,052)	(14,873)
British pound forward purchase contracts [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ 4,481	$ 0	$ (805)	$ 0