Risk Management and Use of Derivative Financial Instruments (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest rate cap
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Amounts attributable to noncontrolling interests	$ 400,000	$ (100,000)	$ (1,000,000)
Interest rate cap | Cash Flow Hedging
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	811,000	(244,000)	(2,221,000)
Interest rate swap | Cash Flow Hedging
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(11,046,000)	(6,864,000)	(1,073,000)
Foreign currency forward | Cash Flow Hedging
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(3,030,000)	0	0
Foreign currency forward | Net Investment Hedging
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(734,000)	(4,809,000)	(1,081,000)
Foreign currency collars | Cash Flow Hedging
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(2,951,000)	6,698,000	0
Put option | Cash Flow Hedging
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ 192,000	$ 0	$ 0