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Note 4 - Securities (Details Textual) $ in Thousands | Sep. 30, 2021 USD ($) | Dec. 31, 2020 USD ($)
--- | --- | ---
Number of Temporarily Impaired Securities | 229 |
Available-for-sale and Held to Maturity Securities Continuous Unrealized Loss Position Fair Value | $ 254,651 |
Continuous Unrealized Loss Position Aggregate Losses | $ 5,644 |
Number of Temporarily Impaired Securities Greater than Twelve Months | 10 |
Continuous Unrealized Loss Position Twelve Months or Longer Fair Value | $ 15,116 | $ 4,695
Continuous Unrealized Loss Position 12 Months or Longer Aggregate Losses | 513 | 5
National Bank of Blacksburg [Member] | Federal Home Loan Bank of Atlanta [Member] |  |
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged | 596,772 |
Restricted Stock [Member] |  |
Restricted Investments | $ 845 | 1,279
US Government Agencies Debt Securities [Member] |  |
Number of Temporarily Impaired Securities | 1 |
Available-for-sale and Held to Maturity Securities Continuous Unrealized Loss Position Fair Value | $ 944 |
Continuous Unrealized Loss Position Aggregate Losses | 53 |
Continuous Unrealized Loss Position Twelve Months or Longer Fair Value | 944 | 0
Continuous Unrealized Loss Position 12 Months or Longer Aggregate Losses | $ 53 | 0
US States and Political Subdivisions Debt Securities [Member] |  |
Number of Temporarily Impaired Securities | 6 |
Continuous Unrealized Loss Position Twelve Months or Longer Fair Value | $ 9,026 | 635
Continuous Unrealized Loss Position 12 Months or Longer Aggregate Losses | $ 313 | $ 3
Collateralized Mortgage Backed Securities [Member] |  |
Number of Temporarily Impaired Securities | 3 |
Available-for-sale and Held to Maturity Securities Continuous Unrealized Loss Position Fair Value | $ 5,146 |
Continuous Unrealized Loss Position Twelve Months or Longer Fair Value | $ 147 |

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- Definition Amount of the excess of amortized cost basis over fair value of securities that have been in a loss position for twelve months or longer for securities. + References No definition available. + Details
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- Definition Amount of the collateral pledged in support of federal home loan bank advances outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822 + Details
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