XML 50 R38.htm IDEA: XBRL DOCUMENT
v3.19.1

General (Details) - USD ($) $ in Thousands |  | 3 Months Ended
--- | --- | ---
Jan. 01, 2019 | Mar. 31, 2019 | Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Unrealized losses on securities transferred from held to maturity to available for sale |  | $ 431 | $ 0
Accounting Standards Update 2017-12 |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Securities available for sale | $ 23,400 |  |
Held-to-maturity securities | 23,400 |  |
Unrealized losses on securities transferred from held to maturity to available for sale | $ 431 | $ 431 |

X
- Definition Debt Securities, Available-For-Sale, Amortized Cost + References No definition available. + Details
Name: | fxnc_DebtSecuritiesAvailableForSaleAmortizedCost
Namespace Prefix: | fxnc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt Securities, Held-To-Maturity + References No definition available. + Details
Name: | fxnc_DebtSecuritiesHeldToMaturity
Namespace Prefix: | fxnc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount before tax and reclassification adjustments of unrealized holding gain (loss) related to transfers of securities into the available-for-sale classification and out of the held-to-maturity classification. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e24883-111560 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 16 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e709-108580 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e689-108580 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 10 -Subparagraph (c),(d) -URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e24820-111560 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e716-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentForHeldToMaturityTransferredToAvailableForSaleSecuritiesBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=fxnc_AccountingStandardsUpdate201712Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |