Derivatives and Hedging Activities (Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Position) (Details) (Designated as Hedging Instrument [Member], Interest Rate Contract [Member], Cash Flow Hedging [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in accumulated other comprehensive income on interest rate derivatives (effective portion)	$ (6,883)	$ 14,058	$ (4,247)	$ 12,881
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)	$ 0	$ (1,272)	$ 0	$ (1,955)