Derivatives and Hedging Activities (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative asset	$ 2,093	$ 5,509
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Costs and Other Assets, Net [Member]
Derivatives, Fair Value [Line Items]
Derivative asset	326	568
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Deferred Costs and Other Assets, Net [Member]
Derivatives, Fair Value [Line Items]
Derivative asset	1,767	4,941
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Deferred Rent, Derivative Liabilities and Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability	$ (9,409)	$ (7,384)