Interest Rate Derivatives and Hedging Activities (Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance) (Details) - Cash Flow Hedging - Interest rate swaps, net - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss recognized in accumulated other comprehensive income (loss) from interest rate derivatives (effective portion)	$ (100)	$ (1,575)	$ (1,719)	$ (2,232)
Amount of loss recognized in loss on derivative instruments (ineffective portion and amount excluded from effectiveness testing)	0	0	(4)	0
Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss reclassified from accumulated other comprehensive income (loss) into income as interest expense (effective portion)	$ (527)	$ (540)	$ (1,053)	$ (1,071)