Risk Management and Use of Derivative Financial Instruments - Information Regarding Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value
Derivative assets, fair value, net	$ 16,798	$ 41,502
Derivative liability, fair value, net	(5,411)	(6,188)
Designated as hedging | Other assets | Foreign currency forward contracts
Derivatives, Fair Value
Derivative assets, fair value, net	14,382	38,735
Designated as hedging | Other assets | Interest rate swap
Derivatives, Fair Value
Derivative assets, fair value, net	314	54
Designated as hedging | Other assets | Interest rate caps
Derivatives, Fair Value
Derivative assets, fair value, net	201	79
Designated as hedging | Other assets | Foreign currency collars
Derivatives, Fair Value
Derivative assets, fair value, net	0	522
Designated as hedging | Accounts payable, accrued expenses and other liabilities | Interest rate swap
Derivatives, Fair Value
Derivative liability, fair value, net	(3,852)	(6,011)
Designated as hedging | Accounts payable, accrued expenses and other liabilities | Foreign currency collars
Derivatives, Fair Value
Derivative liability, fair value, net	(1,431)	(4)
Not designated | Other assets | Foreign currency forward contracts
Derivatives, Fair Value
Derivative assets, fair value, net	86	0
Not designated | Other assets | Stock warrants
Derivatives, Fair Value
Derivative assets, fair value, net	1,815	1,848
Not designated | Other assets | Swaption
Derivatives, Fair Value
Derivative assets, fair value, net	0	264
Not designated | Accounts payable, accrued expenses and other liabilities | Interest rate swap
Derivatives, Fair Value
Derivative liability, fair value, net	$ (128)	$ (173)