Risk Management and Use of Derivative Financial Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Derivatives Not Designated as Hedging Instruments
Derivative assets	$ 8,458	$ 12,586
Derivative liabilities	(23,816)	(8,906)
Interest rate cap
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Assets At Fair Value	1	80
Interest rate swap
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Liabilities At Fair Value	(20,142)	(8,682)
Stock warrants
Derivatives Not Designated as Hedging Instruments
Other Derivatives Not Designated As Hedging Instruments Assets At Fair Value	1,485	1,419
Foreign currency forward
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Assets At Fair Value	4,229	5,206
Derivative Instruments In Hedges Liabilities At Fair Value	(2,533)	0
Foreign currency collars
Derivative Instruments Designated as Hedging Instruments
Derivative Instruments In Hedges Assets At Fair Value	2,743	5,657
Put option
Derivatives Not Designated as Hedging Instruments
Other Derivatives Not Designated As Hedging Instruments Assets At Fair Value	0	(224)
Other Derivatives Not Designated As Hedging Instruments Liabilities At Fair Value	0	224
Embedded derivatives
Derivatives Not Designated as Hedging Instruments
Other Derivatives Not Designated As Hedging Instruments Liabilities At Fair Value	$ 1,141	$ 0