Risk Management and Use of Derivative Financial Instruments - Derivative Gain Loss Reclassified From OCI (Details) - Designated as Cash Flow Hedging Instruments - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)	$ 4,366	$ 1,858	$ 7,911	$ 5,313
Foreign currency forward contracts | Other gains and (losses)
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)	2,917	2,120	5,716	4,554
Foreign currency collars | Other gains and (losses)
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)	1,917	1,285	2,901	2,373
Interest rate swaps and caps | Interest expense
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)
Amount of Gain (Loss) on Derivatives Reclassified from Other Comprehensive Income (Loss)	$ (468)	$ (1,547)	$ (706)	$ (1,614)