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Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Impaired Loans, Average Investment and Interest Income (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Average recorded investment in impaired loans(1) | [1],[2] | $ 12,684 |  | $ 12,541 | $ 13,344 | [3]
Interest income recognized on impaired loans, after designation as impaired |  | 414 |  | 387 | 528 | [3]
Real Estate Construction Portfolio Segment[Member] | Construction, 1-4 Family Residential [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 2,697 |  | 3,323 | 3,298 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 108 |  | 133 | 177 |
Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 891 |  | 1,107 | 781 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 40 |  | 30 | 57 |
Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 162 |  | 188 | 185 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 7 |  | 8 | 11 |
Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 661 |  | 333 | 329 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 18 |  | 12 | 1 |
Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 298 |  | 310 | 748 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 12 |  | 12 | 16 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 3,934 |  | 3,420 | 4,047 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 145 |  | 140 | 200 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 2,829 |  | 2,658 | 2,638 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 55 |  | 45 |  |
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2],[3] | 1,188 |  | 1,187 | 1,282 |
Interest income recognized on impaired loans, after designation as impaired | [3] | 28 |  | 6 | 64 |
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |  |
Average recorded investment in impaired loans(1) | [2] | 24 | [3] | 15 | 36 |
Interest income recognized on impaired loans, after designation as impaired |  | $ 1 | [3] | $ 1 | $ 2 | [3]
[1] | Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.
[2] | Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.
[3] | Only classes with impaired loans are shown.

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