Risk Management and Use of Derivative Financial Instruments (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Amount of Gain (Loss) Reclassified from Other Comprehensive Income (Loss) into Income (Effective Portion)
Amount of Gain (Loss) Reclassified from Other Comprehensive Income (Loss) into Income (Effective Portion)	$ 303	$ 383	$ 358	$ 618
Interest rate swaps | Interest expense
Amount of Gain (Loss) Reclassified from Other Comprehensive Income (Loss) into Income (Effective Portion)
Amount of Gain (Loss) Reclassified from Other Comprehensive Income (Loss) into Income (Effective Portion)	(1,869)	(1,913)	(5,492)	(6,044)
Foreign currency forward contracts | Other income and (expense)
Amount of Gain (Loss) Reclassified from Other Comprehensive Income (Loss) into Income (Effective Portion)
Amount of Gain (Loss) Reclassified from Other Comprehensive Income (Loss) into Income (Effective Portion)	$ 2,172	$ 2,296	$ 5,850	$ 6,662