Risk Management and Use of Derivative Financial Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value
Derivative assets, fair value, net	$ 32,094	$ 11,148
Derivative liability, fair value, net	(17,458)	(27,003)
Foreign currency forward | Designated as hedging | Other assets
Derivatives, Fair Value
Derivative assets, fair value, net	24,051	2,002
Foreign currency forward | Designated as hedging | Accounts payable, accrued expenses and other liabilities
Derivatives, Fair Value
Derivative liability, fair value, net	0	(11,928)
Foreign currency forward | Not designated | Other assets
Derivatives, Fair Value
Derivative assets, fair value, net	5,120	1,521
Foreign currency forward | Not designated | Accounts payable, accrued expenses and other liabilities
Derivatives, Fair Value
Derivative liability, fair value, net	(2,904)	0
Interest rate swap | Designated as hedging | Other assets
Derivatives, Fair Value
Derivative assets, fair value, net	71	1,895
Interest rate swap | Designated as hedging | Accounts payable, accrued expenses and other liabilities
Derivatives, Fair Value
Derivative liability, fair value, net	(14,554)	(12,911)
Foreign currency collars | Designated as hedging | Other assets
Derivatives, Fair Value
Derivative assets, fair value, net	0	429
Embedded derivatives | Not designated | Other assets
Derivatives, Fair Value
Derivative assets, fair value, net	499	2,314
Embedded derivatives | Not designated | Accounts payable, accrued expenses and other liabilities
Derivatives, Fair Value
Derivative liability, fair value, net	0	(2,164)
Stock warrants | Not designated | Other assets
Derivatives, Fair Value
Derivative assets, fair value, net	1,848	1,782
Swaption | Not designated | Other assets
Derivatives, Fair Value
Derivative assets, fair value, net	$ 505	$ 1,205