Risk Management and Use of Derivative Financial Instruments (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ 10,199,000	$ (5,650,000)
Amounts attributable to noncontrolling interests	100,000	100,000
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	147,000	75,000
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	1,967,000	(694,000)
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	5,205,000	(1,263,000)
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	1,863,000	(1,343,000)
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	1,017,000	(2,617,000)
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	$ 0	$ 192,000