XML 106 R91.htm IDEA: XBRL DOCUMENT v3.21.1

Note 19 - Fair Value Measurements - Quantitative Information About Level 3 Fair Value Measurements (Details) - Impaired Loans [Member] - Fair Value, Nonrecurring [Member] $ in Thousands		Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Assets, Fair Value		$ 3,595	$ 406
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value		$ 3,595	$ 406
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Cost to Sell [Member]
Measurement input	[1]	0.1000	0.1000
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Discount Rate [Member]
Measurement input	[1]	0.0650
Fair Value, Inputs, Level 3 [Member] | Valuation Technique, Property Appraisals [Member]
Assets, Fair Value		$ 2,205	$ 406
Fair Value, Inputs, Level 3 [Member] | Valuation Technique, Discounted Cash Flow [Member]
Assets, Fair Value		$ 1,390
[1] Unobservable inputs were weighted by the relative fair value of the instruments.

X

- Definition

Value of input used to measure impaired loans.

+ References

No definition available.

+ Details

Name:	fxnc_ImpairedLoansMeasurementInput
Namespace Prefix:	fxnc_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=fxnc_ImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputCostToSellMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ValuationTechniqueAxis=fxnc_ValuationTechniquePropertyAppraisalsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_ValuationTechniqueDiscountedCashFlowMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: