Derivatives and Hedging Activities (Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Position) (Details) (Cash Flow Hedging [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss reclassified from accumulated other comprehensive income into income as interest expense (effective portion)	$ (371)	$ (79)
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in accumulated other comprehensive income on interest rate derivatives (effective portion)	(16,448)	6,946
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss reclassified from accumulated other comprehensive income into income as interest expense (effective portion)	$ 9,446	$ 4,535