Risk Management and Use of Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Loss (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	$ (12,312)	$ 22,942
Interest rate swaps | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Loss (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	(2,462)	(1,451)
Foreign currency forward contracts | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Loss (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	(8,855)	24,205
Foreign currency forward contracts | Net Investment Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Loss (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	(585)	188
Foreign currency collars | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Loss (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	(395)	$ 0
Foreign currency collars | Net Investment Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive Loss (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	$ (15)