Risk Management and Use of Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss) Activity
Amount of Gain (Loss) Recognized in Other Comprehensive (Loss) Income on Derivatives (Effective Portion)	$ 29,317	$ 23,395	$ (506)
Derivatives in Cash Flow Hedging Relationships | Foreign currency contracts
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss) Activity
Amount of Gain (Loss) Recognized in Other Comprehensive (Loss) Income on Derivatives (Effective Portion)	15,949	23,167	(5,211)
Derivatives in Cash Flow Hedging Relationships | Foreign currency collars
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss) Activity
Amount of Gain (Loss) Recognized in Other Comprehensive (Loss) Income on Derivatives (Effective Portion)	7,769	0	0
Derivatives in Cash Flow Hedging Relationships | Interest rate swap
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss) Activity
Amount of Gain (Loss) Recognized in Other Comprehensive (Loss) Income on Derivatives (Effective Portion)	(284)	(2,628)	4,720
Derivatives in Cash Flow Hedging Relationships | Interest rate caps
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss) Activity
Amount of Gain (Loss) Recognized in Other Comprehensive (Loss) Income on Derivatives (Effective Portion)	64	290	(15)
Derivatives in Net Investment Hedging Relationships | Foreign currency contracts
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss) Activity
Amount of Gain (Loss) Recognized in Other Comprehensive (Loss) Income on Derivatives (Effective Portion)	$ 5,819	$ 2,566	$ 0