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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (6,806)	$ 2,706	$ (16,237)	$ (3,604)
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	(5,064)	7,521	(14,366)	1,682
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	$ (1,742)	$ (4,815)	$ (1,871)	$ (5,286)