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Note 11 - Minimum Regulatory Capital Requirement (Details Textual) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
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National Bank of Blacksburg [Member] |  |
Banking Regulation, Risk-Weighted Assets, Actual | $ 932,364 | $ 816,962

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- Definition Amount of risk-weighted assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
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Data Type: | na
Balance Type: |
Period Type: |