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Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) shares in Thousands, $ in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2020 | Dec. 31, 2017
Debt Securities, Held-to-maturity, Transfer, Amount |  |  | $ 119,790 |  |
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, before Tax |  |  | 1,128 |  |
Number of Days of Delinquent Loans Nonaccrual of Interest (Day) | 90 days |  |  |  |
Minimum Number of Days of Discontinued Loan Payments for Modified Loan to be Placed on Nonaccrual (Day) | 90 days |  |  |  |
Number of Days Past Due (Day) | 30 days |  |  |  |
Threshold for Designation to Impaired Status | $ 250 |  |  |  |
Minimum Number of Days Consumer Loans are Past Due for Losses to be Charged Off (Day) | 120 days |  |  |  |
Maximum Number of Days Consumer Loans are Past Due for Losses to be Charged Off (Day) | 180 days |  |  |  |
Number of Days Loans Secured by Residential Or Commercial Real Estate Are Past Due for Losses to Be Carged Off (Day) | 180 days |  |  |  |
Period of Time Between Issuance of Loan Commitment and Closing and Sale of Loans Lower Range (Day) | 30 days |  |  |  |
Period of Time Between Issuance of Loan Commitments and Closing and Sale of Loans Upper Range (Day) | 60 days |  |  |  |
Market Capitalization | $ 201,387 |  |  | $ 164,381 |
Stockholders' Equity Attributable to Parent, Ending Balance | 200,607 | $ 183,726 | 190,238 | $ 202,194 | $ 184,896
Goodwill, Impairment Loss | $ 0 | 0 | 0 |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | 0 |  |  |  |
Advertising Expense | $ 99 | 120 | $ 106 |  |
Number of Loan Modifications for COVID-19 Related Accommodations | 388 |  |  |  |
Principal Balance of Loans with COVID-19 Related Accommodations | $ 182,829 |  |  |  |
Loans and Leases Receivable, Net Amount, Total | 760,318 | $ 726,588 |  |  |
SBA CARES Act Paycheck Protection Program [Member] |  |  |  |  |
Loans and Leases Receivable, Net Amount, Total | $ 35,992 |  |  |  |
National Bank of Blacksburg [Member] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Parent | 100.00% |  |  |  |
Minimum [Member] |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life (Year) | 10 years |  |  |  |
Maximum [Member] |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life (Year) | 12 years |  |  |  |
Building [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 40 years |  |  |  |
Furniture and Fixtures [Member] | Minimum [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 3 years |  |  |  |
Furniture and Fixtures [Member] | Maximum [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 10 years |  |  |  |
Computer Equipment [Member] |  |  |  |  |
Property, Plant and Equipment, Useful Life (Year) | 3 years |  |  |  |

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