Risk Management and Use of Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 5,689	$ 537	$ 0
Interest rate swap | Interest expense
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	5,249	429	0
Stock warrants | Other income and (expenses)
Amount of Gain (Loss) Recognized in Income on Derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 440	$ 108	$ 0