Fair Value of Assets and Liabilities (Schedule Of Level 3 Assets Measured At Fair Value On Nonrecurring Basis) (Details) - Nonrecurring [Member] - (Level 3) Significant Other Unobservable Inputs [Member] - USD ($) $ in Thousands		Sep. 30, 2020		Dec. 31, 2019
Impaired Loans [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets measured at fair value	[1],[2]	$ 2,553		$ 5,991
Impaired Loans [Member] | Business Asset Valuation Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets measured at fair value	[3],[4]			$ 5,306
Impaired Loans [Member] | Minimum [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[1],[2]	15.00%		15.00%
Impaired Loans [Member] | Minimum [Member] | Business Asset Valuation Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[3],[4]			10.00%
Impaired Loans [Member] | Maximum [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[1],[2]	50.00%		55.00%
Impaired Loans [Member] | Maximum [Member] | Business Asset Valuation Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[3],[4]			73.00%
Impaired Loans [Member] | Weighted Average [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[1],[2]	42.00%		44.00%
Impaired Loans [Member] | Weighted Average [Member] | Business Asset Valuation Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[3],[4]			70.00%
Foreclosed Real Estate [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets measured at fair value	[1],[2]			$ 797
Foreclosed Real Estate [Member] | Minimum [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[1],[2]			22.00%
Foreclosed Real Estate [Member] | Maximum [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[1],[2]			22.00%
Foreclosed Real Estate [Member] | Weighted Average [Member] | Appraisal Adjustments [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	[1],[2]			22.00%
Mortgage Servicing Rights [Member] | Multiple Of Annual Service Fee [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assets measured at fair value		$ 548	[1],[2]	$ 1,047
Mortgage Servicing Rights [Member] | Minimum [Member] | Multiple Of Annual Service Fee [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range		17.00%	[1],[2]	7.90%
Mortgage Servicing Rights [Member] | Maximum [Member] | Multiple Of Annual Service Fee [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range		20.20%	[1],[2]	8.90%
Mortgage Servicing Rights [Member] | Weighted Average [Member] | Multiple Of Annual Service Fee [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range		19.40%	[1],[2]	8.70%

[1] Appraisal amounts may be adjusted downward by the Corporation's management for qualitative factors such as economic conditions and estimated liquidation expenses. The range of liquidation expense adjustments are presented as a percent of the appraisal.

[2] Fair value is generally determined through independent appraisals, which generally include various level 3 inputs that are not identifiable.

[3] Business asset valuation may be adjusted downward by the corporation's management qualitative factors such as economic conditions and estimated liquidation expenses. The range of liquidation expenses adjustments are presented as a percent of the financial statement book value.

[4] Fair value is generally determined through customer-provided financial statements and bankruptcy court documents.