Risk Management and Use of Derivative Financial Instruments - Derivative Gain Loss Reclassified From OCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Amount of Gain (Loss) Reclassified from Other Comprehensive Income into Income (Effective Portion)
Derivatives, income (loss) reclassified from AOCI to Income, effective portion, net	$ 1,380	$ 303	$ 4,090	$ 358
Foreign currency forward contracts | Other income and (expenses)
Amount of Gain (Loss) Reclassified from Other Comprehensive Income into Income (Effective Portion)
Derivatives, income (loss) reclassified from AOCI to Income, effective portion, net	1,949	2,172	5,968	5,850
Interest rate swaps | Interest expense
Amount of Gain (Loss) Reclassified from Other Comprehensive Income into Income (Effective Portion)
Derivatives, income (loss) reclassified from AOCI to Income, effective portion, net	$ (569)	$ (1,869)	$ (1,878)	$ (5,492)