Risk Management and Use of Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Amount of Gain Recognized in Income on Derivatives
Amount of Gain Recognized in Income on Derivatives	$ 1,275	$ 881	$ 2,126	$ 4,571
Interest rate swap | Interest expense
Amount of Gain Recognized in Income on Derivatives
Amount of Gain Recognized in Income on Derivatives	1,007	801	1,992	4,211
Stock warrants | Other income and (expenses)
Amount of Gain Recognized in Income on Derivatives
Amount of Gain Recognized in Income on Derivatives	$ 268	$ 80	$ 134	$ 360