Risk Management and Use of Derivative Financial Instruments (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Amount of Gain (Loss) Reclassified from Other Comprehensive Loss into Income (Effective Portion)
Derivatives, gain (loss) reclassified from AOCI to Income, effective portion, net	$ 579	$ 845
Foreign currency forward contracts | Other income and (expense)
Amount of Gain (Loss) Reclassified from Other Comprehensive Loss into Income (Effective Portion)
Derivatives, gain (loss) reclassified from AOCI to Income, effective portion, net	2,380	3,129
Interest rate swaps | Interest expense
Amount of Gain (Loss) Reclassified from Other Comprehensive Loss into Income (Effective Portion)
Derivatives, gain (loss) reclassified from AOCI to Income, effective portion, net	$ (1,801)	$ (2,284)