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This element represents the fair value of other real estate owned, net of valuation allowance.No definition available.false2Other real estate owned, net85false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse21false USDtruefalse$c20130630_FairValueByFairValueHierarchyLevelAxis_FairValueInputsLevel3Member_FairValueByMeasurementFrequencyAxis_FairValueMeasurementsNonrecurringMemberhttp://www.sec.gov/CIK0001083643instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseFair Value, Measurements, Nonrecurring [Member]us-gaap_FairValueByMeasurementFrequencyAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_FairValueMeasurementsNonrecurringMemberus-gaap_FairValueByMeasurementFrequencyAxisexplicitMemberfalsefalseSignificant Other Unobservable Inputs (Level 3) [Member]us-gaap_FairValueByFairValueHierarchyLevelAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_FairValueInputsLevel3Memberus-gaap_FairValueByFairValueHierarchyLevelAxisexplicitMemberU002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Fair Value, Measurements, Nonrecurring [Member] | Significant Other Unobservable Inputs (Level 3) [Member]86true 4fbss_FinancialAssetsMeasuredAtFairValueOnNonrecurringBasisAbstractfbss_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Financial Assets Measured at Fair Value on a Nonrecurring Basis [Abstract]87false 5fbss_ImpairedLoansFairValueDisclosurefbss_falsedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse296000296USD$falsefalsefalse2truefalsefalse377000377USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThis element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents impaired loan receivable as presented on the statement of financial position which may include impaired mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts, or any other loans which are due the Company as of the balance sheet date.No definition available.false2Impaired loans, net88false 5fbss_OtherRealEstateOwnedNetFairValueDisclosurefbss_falsedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse00USD$falsetruefalse2truefalsefalse00USD$falsetruefalsexbrli:monetaryItemTypemonetaryThis element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This element represents the fair value of other real estate owned, net of valuation allowance.No definition available.false2Other real estate owned, netfalseFair Value Measurement, Assets and Liabilities Measured at Fair Value on Recurring and Nonrecurring Basis (Details) (USD $)ThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://fauquierbank.com/role/FairValueMeasurementAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringAndNonrecurringBasisDetails288