Risk Management and Use of Derivative Financial Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	$ 15,627	$ 12,586
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Net	(14,765)	(8,906)
Designated as Hedging Instrument [Member] | Other Assets [Member] | Interest Rate Cap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	9	80
Designated as Hedging Instrument [Member] | Other Assets [Member] | Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	8,299	5,206
Designated as Hedging Instrument [Member] | Other Assets [Member] | Foreign Currency Collars [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	5,900	5,657
Designated as Hedging Instrument [Member] | Other Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Net	(14,765)	(8,682)
Not Designated as Hedging Instrument [Member] | Other Assets [Member] | Stock warrants [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	1,419	1,419
Not Designated as Hedging Instrument [Member] | Other Assets [Member] | Put Option [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Net	0	224
Not Designated as Hedging Instrument [Member] | Other Liabilities [Member] | Put Option [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Net	$ 0	$ (224)