Risk Management and Use of Derivative Financial Instruments - Derivative Gain Loss Recognized in OCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss)
Amount of gain (loss) recognized on derivatives in other comprehensive income (loss)	$ (16,729)	$ 13,700	$ (12,829)	$ 14,180
Derivatives in Cash Flow Hedging Relationships  | Foreign currency collars
Derivative Instruments, Gain (Loss)
Amount of gain (loss) recognized on derivatives in other comprehensive income (loss)	(17,029)	13,661	(5,524)	17,539
Derivatives in Cash Flow Hedging Relationships  | Interest rate swaps
Derivative Instruments, Gain (Loss)
Amount of gain (loss) recognized on derivatives in other comprehensive income (loss)	312	(398)	(2,047)	(2,775)
Derivatives in Cash Flow Hedging Relationships  | Interest rate caps
Derivative Instruments, Gain (Loss)
Amount of gain (loss) recognized on derivatives in other comprehensive income (loss)	4	50	5	199
Derivatives in Cash Flow Hedging Relationships  | Foreign currency forward contracts
Derivative Instruments, Gain (Loss)
Amount of gain (loss) recognized on derivatives in other comprehensive income (loss)	0	361	(5,272)	(809)
Derivatives in Net Investment Hedging Relationships | Foreign currency collars
Derivative Instruments, Gain (Loss)
Amount of gain (loss) recognized on derivatives in other comprehensive income (loss)	(16)	18	9	19
Derivatives in Net Investment Hedging Relationships | Foreign currency forward contracts
Derivative Instruments, Gain (Loss)
Amount of gain (loss) recognized on derivatives in other comprehensive income (loss)	$ 0	$ 8	$ 0	$ 7