Derivatives and Hedging Activity (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effect of derivative instruments on the Consolidated Statements of Operations
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net, Total	$ (4,834,000)	$ (6,851,000)	$ (7,649,000)
Interest rate products | Cash Flow Hedging
Effect of derivative instruments on the Consolidated Statements of Operations
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net, Total	(8,695,000)	(469,000)	(4,924,000)
Interest rate products | Interest expense | Cash Flow Hedging
Effect of derivative instruments on the Consolidated Statements of Operations
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net, Total	(4,834,000)	(6,851,000)	(7,649,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net, Total	3,000		0
Interest rate products | Other income/(expense)
Effect of derivative instruments on the Consolidated Statements of Operations
Derivative Instruments, Gain (Loss) Recognized in Income, Net, Total	$ (4,000)	$ 271,000	$ 290,000