Derivatives and Hedging Activities (Schedule of Interest Rate Derivatives) (Details) (Cash Flow Hedging [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2014 derivative
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Number of Instruments	6
Derivative, Notional Amount	$ 734,800
Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Number of Instruments	17
Derivative, Notional Amount	1,174,544
Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Number of Instruments	5
Derivative, Notional Amount	234,800
Interest Rate Cap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Number of Instruments	1
Derivative, Notional Amount	$ 500,000