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Allowance for Loan Losses and Credit Quality of Loans, Impaired Loans (Details) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Allowance for Loan Losses and Credit Quality of Loans [Abstract] |  |
Threshold balance for classified loans to be evaluated individually for impairment | $ 750 |
Total [Abstract] |  |
Recorded investment balance (book) | 21,082 | $ 21,138
Unpaid principal balance (legal) | 28,690 | 28,120
Related allowance | 42 | 57
Acquired impaired loans specifically evaluated for impairment | 0 | 0
Originated Loans [Member] |  |
With an allowance recorded [Abstract] |  |
Recorded investment balance (book) | 20,981 | 21,035
Unpaid principal balance (legal) | 28,583 | 28,011
Originated Loans [Member] | Commercial Loans [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) | 5,905 | 5,773
Unpaid principal balance (legal) | 9,193 | 8,848
With an allowance recorded [Abstract] |  |
Recorded investment balance (book) | 101 | 103
Unpaid principal balance (legal) | 107 | 109
Total [Abstract] |  |
Related allowance | 42 | 57
Originated Loans [Member] | Commercial Loans [Member] | C&I [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) | 430 |
Unpaid principal balance (legal) | 696 |
With an allowance recorded [Abstract] |  |
Recorded investment balance (book) | 27 |
Unpaid principal balance (legal) | 26 |
Total [Abstract] |  |
Related allowance | 27 |
Originated Loans [Member] | Commercial Loans [Member] | CRE [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) | 4,397 |
Unpaid principal balance (legal) | 6,362 |
With an allowance recorded [Abstract] |  |
Recorded investment balance (book) | 74 |
Unpaid principal balance (legal) | 81 |
Total [Abstract] |  |
Related allowance | 15 |
Originated Loans [Member] | Commercial Loans [Member] | Commercial [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 0
Unpaid principal balance (legal) |  | 251
Originated Loans [Member] | Commercial Loans [Member] | Commercial Real Estate [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 2,211
Unpaid principal balance (legal) |  | 3,979
With an allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 76
Unpaid principal balance (legal) |  | 82
Total [Abstract] |  |
Related allowance |  | 30
Originated Loans [Member] | Commercial Loans [Member] | Agricultural [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 452
Unpaid principal balance (legal) |  | 465
With an allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 27
Unpaid principal balance (legal) |  | 27
Total [Abstract] |  |
Related allowance |  | 27
Originated Loans [Member] | Commercial Loans [Member] | Agricultural Real Estate [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 2,250
Unpaid principal balance (legal) |  | 2,423
Originated Loans [Member] | Commercial Loans [Member] | Business Banking [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) | 1,078 | 860
Unpaid principal balance (legal) | 2,135 | 1,730
Originated Loans [Member] | Consumer Loans [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) | 8,305 | 8,432
Unpaid principal balance (legal) | 10,293 | 10,383
Originated Loans [Member] | Consumer Loans [Member] | Dealer Finance [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) | 198 |
Unpaid principal balance (legal) | 216 |
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) | 8,107 |
Unpaid principal balance (legal) | 10,077 |
Originated Loans [Member] | Consumer Loans [Member] | Indirect [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 131
Unpaid principal balance (legal) |  | 143
Originated Loans [Member] | Consumer Loans [Member] | Home Equity [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 8,027
Unpaid principal balance (legal) |  | 9,966
Originated Loans [Member] | Consumer Loans [Member] | Direct [Member] |  |
With no related allowance recorded [Abstract] |  |
Recorded investment balance (book) |  | 274
Unpaid principal balance (legal) |  | 274
Originated Loans [Member] | Residential Real Estate Mortgages [Member] |  |
With an allowance recorded [Abstract] |  |
Recorded investment balance (book) | 6,771 | 6,830
Unpaid principal balance (legal) | $ 9,097 | $ 8,780

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