XML 23 R78.htm IDEA: XBRL DOCUMENT v2.4.1.9
Benefit Plans - Additional Information (Detail) (USD $)
 0 Months Ended 12 Months Ended
May 31, 2013
Jan. 01, 2000
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]            
Number of highest-paid consecutive years for benefits     5 years      
Percentage of first employee compensation for which company makes matching contribution     1.00%fxnc_DefinedContributionPlanPercentageOfEmployerMatchingContributionOfFirstOnePercentOfEmployeeContribution      
Company contribution on employee specific contribution     50.00%fxnc_DefinedContributionPlanPercentageOfEmployerMatchingContributionOfStatedPercentageOfEmployeeContribution      
Number of hours in service required for the contribution to be allocated     1000 hours      
Minimum eligibility for employees under 401(k) Plan, age     19 years      
Number of plan service years after which employer matching contribution vest     2 years      
Expense attributable to the Plan amounted     $ 306,000us-gaap_DefinedContributionPlanCostRecognized $ 249,000us-gaap_DefinedContributionPlanCostRecognized $ 219,000us-gaap_DefinedContributionPlanCostRecognized  
Percentage of vested participants   100.00%fxnc_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentageUnderAwardRequisiteServicePeriod        
Participants years of credited service   2 years        
Compensation expense for ESOP     0us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense 0us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense 0us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense  
Shares of the Company held by the ESOP     173,823us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP 169,882us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP 134,609us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP  
Recorded gain from termination of post retirement benefit liability 543,000us-gaap_DefinedBenefitPlanOtherChanges          
Minimum [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of employee for which company makes specified contribution     2.00%fxnc_DefinedContributionPlanStatedPercentageOfEmployeesContribution
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		      
Maximum [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Percentage of employee for which company makes specified contribution     6.00%fxnc_DefinedContributionPlanStatedPercentageOfEmployeesContribution
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		      
Postretirement Life Insurance [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Related effect on net income recognized expense (benefit)         21,000fxnc_ExpenseBenefitRecognizedUnderPlan
/ us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsByTypeOfDeferredCompensationAxis
= us-gaap_DefinedBenefitPostretirementLifeInsuranceMember		  
Defined Benefit Pension Plan [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Minimum eligibility for full-time employees, age     21 years      
Effective discount rate     0.25%fxnc_DefinedBenefitPlanSingleEffectiveDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		      
Amount contributed to pension plan     0us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 500,000us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 306,000us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		  
Amount of accumulated benefit obligation for the defined benefit pension plan     5,300,000us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 3,800,000us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 5,100,000us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		  
Defined Benefit Pension Plan [Member] | Scenario, Forecast [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Amount contributed to pension plan, Expected in future           $ 0us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_StatementScenarioAxis
= us-gaap_ScenarioForecastMember
Defined Benefit Pension Plan [Member] | Minimum [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Period of service credit by employee     1 year      
Defined Benefit Pension Plan [Member] | Fixed Income Funds [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Targeted asset allocation on fixed income     40.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_FixedIncomeFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		      
Defined Benefit Pension Plan [Member] | Equity Funds [Member]            
Defined Benefit Plan Disclosure [Line Items]            
Targeted asset allocation on fixed income     60.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_EquityFundsMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember