Risk Management and Use of Derivative Financial Instruments (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Amount of Gain (Loss) Reclassified from Other Comprehensive (Loss) Income into Income (Effective Portion)
Derivatives, gain (loss) reclassified from AOCI to Income, effective portion, net	$ (524)	$ (610)	$ 55	$ 234
Interest rate swaps | Interest expense
Amount of Gain (Loss) Reclassified from Other Comprehensive (Loss) Income into Income (Effective Portion)
Derivatives, gain (loss) reclassified from AOCI to Income, effective portion, net	(1,822)	(1,847)	(3,623)	(4,131)
Foreign currency forward contracts | Other income and (expense)
Amount of Gain (Loss) Reclassified from Other Comprehensive (Loss) Income into Income (Effective Portion)
Derivatives, gain (loss) reclassified from AOCI to Income, effective portion, net	$ 1,298	$ 1,237	$ 3,678	$ 4,365