Risk Management and Use of Derivative Financial Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivatives Not Designated as Hedging Instruments
Derivative assets	$ 14,717	$ 8,458
Derivative liabilities	(18,231)	(23,816)
Interest rate cap
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Assets At Fair Value	0	1
Interest rate swap
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Liabilities At Fair Value	(17,840)	(20,142)
Stock warrants
Derivatives Not Designated as Hedging Instruments
Other Derivatives Not Designated As Hedging Instruments Assets At Fair Value	1,650	1,485
Foreign currency forward
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Assets At Fair Value	8,707	4,229
Derivative Instruments In Hedges Liabilities At Fair Value	(198)	(2,533)
Foreign currency collars
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Assets At Fair Value	3,542	2,743
Put option
Derivatives Not Designated as Hedging Instruments
Other Derivatives Not Designated As Hedging Instruments Assets At Fair Value	818	0
Embedded derivatives
Derivatives Not Designated as Hedging Instruments
Other Derivatives Not Designated As Hedging Instruments Liabilities At Fair Value	$ (193)	$ (1,141)