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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (2,127)	$ (4,253)	$ (18,364)	$ (7,857)
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	(1,414)	(8,734)	(15,780)	(7,052)
British pound forward 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	$ (713)	$ 4,481	$ (2,584)	$ (805)