Risk Management and Use of Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net
Derivatives not in cash flow hedging relationships, gain (loss), net	$ (78)	$ 60	$ (209)	$ 1,839
Embedded derivatives | Other income and expense
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net
Derivatives not in cash flow hedging relationships, gain (loss), net	163	(394)	281	554
Foreign currency forward | Other income and expense
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net
Derivatives not in cash flow hedging relationships, gain (loss), net	(56)	199	(118)	762
Stock warrants | Other income and expense
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net
Derivatives not in cash flow hedging relationships, gain (loss), net	(66)	0	(66)	165
Swaption | Other income and expense
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net
Derivatives not in cash flow hedging relationships, gain (loss), net	(172)	179	(430)	179
Interest rate swap | Interest expense
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net
Derivatives not in cash flow hedging relationships, gain (loss), net	$ 53	$ 76	$ 124	$ 179