Derivative Instruments And Hedging Activities (Schedule Of Notional Values And Fair Values Of Derivative Instruments) (Details) - Cash Flow Interest Rate Contracts [Member] - Designated As Hedging Instrument [Member] - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Value	$ 540,000,000	$ 540,000,000
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 12,038,000	$ 7,995,000