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Note 5 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Impaired Loans, Average Investment and Interest Income (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Average recorded investment in impaired loans(1) |  | $ 5,093 | [1] | $ 5,359 | [1] | $ 9,788 | [2]
Income recognized on impaired loans, after designation as impaired |  | 54 |  | 171 |  | 250 |
Investor Owned Residential Real Estate [Member] | Consumer Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [1] | 196 |  | 439 |  | 808 | [2]
Income recognized on impaired loans, after designation as impaired | [1] | 13 |  | 17 |  | 23 |
Equity Lines [Member] | Consumer Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) |  |  |  | 98 |  |  |
Income recognized on impaired loans, after designation as impaired |  |  |  | 6 |  |  |
Closed End First Liens [Member] | Consumer Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) |  |  |  | 225 | [1] | 1,202 |
Income recognized on impaired loans, after designation as impaired |  |  |  | 11 | [1] | 41 |
Closed End Junior Liens [Member] | Consumer Real Estate Portfolio Segment [Member] | Financing Receivables 30 to 89 Days Past Due [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [3] |  |  |  |  | 159 |
Closed End Junior Liens [Member] | Consumer Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] |  |  |  |  |  |  |
Income recognized on impaired loans, after designation as impaired | [3] |  |  |  |  | 9 |
Commercial Real Estate, Owner Occupied [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [1] | 3,217 |  | 913 |  | 3,038 | [2]
Income recognized on impaired loans, after designation as impaired | [1] | 19 |  | 41 |  | 75 |
Commercial Real Estate Other [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [1] | 790 |  | 2,435 |  | 2,744 | [2]
Income recognized on impaired loans, after designation as impaired | [1] |  |  | 59 |  | 54 |
Multifamily Real Estate [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [1] |  |  | 284 |  | 491 | [2]
Income recognized on impaired loans, after designation as impaired | [1] |  |  | 12 |  | 20 |
Commercial and Industrial [Member] | Commercial Non Real Estate Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [1] | 887 |  | 962 |  | 1,326 | [2]
Income recognized on impaired loans, after designation as impaired | [1] | 22 |  | 25 |  | 27 |
Automobile Loan [Member] | Consumer Non Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [1] | $ 3 |  | $ 3 |  | 20 | [2]
Income recognized on impaired loans, after designation as impaired | [1] |  |  |  |  | $ 1 |
[1] | Only classes with impaired loans are shown.
[2] | Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.
[3] | Only classes with past due or nonaccrual loans are presented

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