Risk Management and Use of Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Amount of Gain (Loss) Recognized in Income on Derivatives
Derivative Instruments Not in Cash Flow Hedging Relationships	$ 1,779	$ (29)
Interest rate swap
Amount of Gain (Loss) Recognized in Income on Derivatives
Derivative Instruments Not in Cash Flow Hedging Relationships	103	(29)
Stock warrants
Amount of Gain (Loss) Recognized in Income on Derivatives
Derivative Instruments Not in Cash Flow Hedging Relationships	165	0
Foreign currency forward
Amount of Gain (Loss) Recognized in Income on Derivatives
Derivative Instruments Not in Cash Flow Hedging Relationships	563	0
Embedded derivatives
Amount of Gain (Loss) Recognized in Income on Derivatives
Derivative Instruments Not in Cash Flow Hedging Relationships	$ 948	$ 0