Derivative Instruments and Hedging Activities (Details 2) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative net gain (loss) recognized in income statement	$ 20,000		$ (1,807,000)		$ 592,000		$ (3,771,000)
Total Return Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative net gain (loss) recognized in income statement	(42,000)		(1,807,000)		633,000		(3,532,000)
Total Return Swap [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative net gain (loss) recognized in income statement	68,000	[1]	2,996,000	[1]	2,279,000	[1]	3,100,000	[1]
Interest rate caps and interest rate swaps [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative net gain (loss) recognized in income statement	$ 62,000		$ 0		$ (41,000)		$ (239,000)

[1] The net gain (loss) recognized in interest expense from the change in fair value of the underlying TRS borrowings was $(68) and $(2,279) for the three and nine months ended September 30, 2014, respectively, and $(2,996) and $(3,100) for the three and nine months ended September 30, 2013, respectively, offsetting the gain (loss) recognized on the TRS.