Risk Management and Use of Derivative Financial Instruments - Derivative Gain (Loss) Reclassified From OCI (Details) - Derivatives in Cash Flow Hedging Relationships - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income	$ 45	$ 396	$ 247	$ 777
Interest rate swaps | Interest expense
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income	(434)	22	(613)	49
Foreign currency forward contracts | Other gains and (losses)
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income	264	338	542	684
Foreign currency collars | Other gains and (losses)
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income	235	39	355	50
Interest rate caps | Interest expense
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income
Amount of Gain on Derivatives Reclassified from Other Comprehensive Income (Loss) into Income	$ (20)	$ (3)	$ (37)	$ (6)