XML 18 R33.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Securities (Details Textual) (USD $) In Millions, unless otherwise specified | 6 Months Ended
--- | ---
Jun. 30, 2012 Contract
Securities (Textual) [Abstract] |
Number of U.S. agency and mortgage-backed securities | 2
Number of obligation of state and political subdivisions in an unrealized loss position | 10
Percentage of investment portfolio | 100.00%
Weighted-average period of re-pricing of portfolio | 4 years
Investment in Federal Home Loan Bank stock | $ 1.5

X
- Definition Investment in federal home loan bank stock. + References No definition available. + Details
Name: | fxnc_InvestmentInFederalHomeLoanBankStock
Namespace Prefix: | fxnc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number obligation of state and political subdivisions in an unrealized loss position. + References No definition available. + Details
Name: | fxnc_NumberObligationOfStateAndPoliticalSubdivisionsInUnrealizedLossPosition
Namespace Prefix: | fxnc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of securities in unrealized loss position. + References No definition available. + Details
Name: | fxnc_NumberOfSecuritiesInUnrealizedLossPosition
Namespace Prefix: | fxnc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of investment portfolio. + References No definition available. + Details
Name: | fxnc_PercentageOfInvestmentPortfolio
Namespace Prefix: | fxnc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | fxnc_SecuritiesTextualAbstract
Namespace Prefix: | fxnc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average period of pricing of portfolio. + References No definition available. + Details
Name: | fxnc_WeightedAveragePeriodOfPricingOfPortfolio
Namespace Prefix: | fxnc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration