Risk Management and Use of Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 373	$ 1,729	$ 851	$ 3,688
Interest rate swap | Interest expense
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	507	1,729	985	3,408
Stock warrants | Other income and (expenses)
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	$ (134)	$ 0	$ (134)	$ 280