Risk Management and Use of Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)	$ (2,572)	$ (3,108)	$ (11,431)	$ 15,949
Foreign currency forward contracts | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)	(4,179)	(978)	(9,324)	15,626
Foreign currency forward contracts | Net Investment Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)	(170)	(20)	(1,431)	366
Interest rate swaps | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)	2,152	(2,110)	(437)	(43)
Foreign currency collars | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)	(325)	0	(181)	0
Foreign currency collars | Net Investment Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)	(13)	0	(21)	0
Interest rate caps | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Income (Loss) (Effective Portion)	$ (37)	$ 0	$ (37)	$ 0