Derivative Instruments (Fair Value Of Derivative Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Customer Counterparties Loan Interest Rate Swap Assets [Member] | Non-hedging interest rate derivatives: | Other Assets
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 86,856	$ 225,480
Derivative, Fair Value	2,039	4,877
Customer Counterparties Loan Interest Rate Swap Liabilities [Member] | Non-hedging interest rate derivatives: | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	426,241	314,450
Derivative, Fair Value	19,452	9,513
Financial Institution Counterparties Loan Interest Rate Swap Asset [Member] | Non-hedging interest rate derivatives: | Other Assets
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	432,755	320,949
Derivative, Fair Value	19,620	9,591
Financial Institution Counterparties Loan Interest Rate Swap Asset [Member] | Derivatives designated as hedges of fair value: | Other Assets
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,961	4,326
Derivative, Fair Value	93	34
Financial Institution Counterparties Loan Interest Rate Swap Liabilities [Member] | Non-hedging interest rate derivatives: | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	86,856	218,924
Derivative, Fair Value	$ 2,039	$ 4,877