Risk Management and Use of Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive (Loss) Income (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	$ 3,455	$ (3,885)	$ (8,858)	$ 19,057
Foreign currency forward contracts | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive (Loss) Income (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	3,711	(7,601)	(5,145)	16,604
Foreign currency forward contracts | Net Investment Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive (Loss) Income (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	(676)	198	(1,261)	386
Foreign currency collars | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive (Loss) Income (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	540	0	145	0
Foreign currency collars | Net Investment Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive (Loss) Income (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	7	0	(8)	0
Interest rate swaps | Cash Flow Hedging
Amount of Gain (Loss) Recognized on Derivatives in Other Comprehensive (Loss) Income (Effective Portion)
Derivatives, gain (loss) recognized in OCI, effective portion, net	$ (127)	$ 3,518	$ (2,589)	$ 2,067