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Note 4 - Loans and Allowance for Loan Losses - Loans Modified in a Troubled Debt Restructuring (Details) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Number of loans | 7 | 7
Pre- modification outstanding principal balance | $ 594 | $ 594
Post- modification principal balance | $ 337 | $ 365
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] |  |
Number of loans | 1 | 1
Pre- modification outstanding principal balance | $ 107 | $ 107
Post- modification principal balance | $ 80 | $ 82
Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] |  |
Number of loans | 3 | 3
Pre- modification outstanding principal balance | $ 318 | $ 318
Post- modification principal balance | $ 141 | $ 165
Real Estate [Member] | Secured by Non-farm, Non-residential Properties [Member] |  |
Number of loans | 1 | 1
Pre- modification outstanding principal balance | $ 53 | $ 53
Post- modification principal balance | $ 36 | $ 37
Commercial and Industrial Loans [Member] |  |
Number of loans | 2 | 2
Pre- modification outstanding principal balance | $ 116 | $ 116
Post- modification principal balance | $ 80 | $ 81

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