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Note 3 - Securities (Details Textual) | 12 Months Ended
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Dec. 31, 2025 USD ($) Securities | Dec. 31, 2024 USD ($)
Marketable Securities [Line Items] |  |
Deferred Tax Asset, Debt Securities, Available-for-Sale, Unrealized Loss | $ 10,889,000 | $ 16,506,000
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions | Securities | 522 |
Debt Securities, Available-for-Sale, Unrealized Loss Position | $ 601,783,000 |
Proceeds from Sale of Debt Securities, Available for Sale | 0 |
Debt Securities, Available-for-Sale, Restricted | 654,370,000 | 536,260,000
National Bank of Blacksburg [Member] | Federal Home Loan Bank of Atlanta [Member] |  |
Marketable Securities [Line Items] |  |
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged | 517,382,000 |
Restricted Stock [Member] |  |
Marketable Securities [Line Items] |  |
Restricted Investments | $ 1,848,000 | 1,848,000
Securities Called [Member] |  |
Marketable Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Realized Gain (Loss) |  | $ 0

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- Definition Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-9 + Details
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