Risk Management and Use of Derivative Financial Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value
Asset Derivatives Fair Value at	$ 3,780	$ 1,745
Liability Derivatives Fair Value at	(21,812)	(24,578)
Interest rate cap | Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value
Asset Derivatives Fair Value at	2	25
Liability Derivatives Fair Value at	0	0
Interest rate swap | Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value
Asset Derivatives Fair Value at	1,618	0
Liability Derivatives Fair Value at	0	0
Interest rate swap | Designated as Hedging Instrument | Accounts Payable and Accrued Liabilities
Derivatives, Fair Value
Asset Derivatives Fair Value at	0	0
Liability Derivatives Fair Value at	(2,734)	(5,825)
Interest rate swap | Not Designated as Hedging Instrument | Accounts Payable and Accrued Liabilities
Derivatives, Fair Value
Asset Derivatives Fair Value at	0	0
Liability Derivatives Fair Value at	(11,995)	(16,686)
Foreign currency contracts | Designated as Hedging Instrument | Accounts Payable and Accrued Liabilities
Derivatives, Fair Value
Asset Derivatives Fair Value at	0	0
Liability Derivatives Fair Value at	(7,083)	(2,067)
Stock warrants | Not Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value
Asset Derivatives Fair Value at	2,160	1,720
Liability Derivatives Fair Value at	$ 0	$ 0