2.4.0.82404401 - Disclosure - Guarantees (Narrative) (Details)truefalseIn Thousands, unless otherwise specifiedfalse1false falsefalseD2013Q2YTDhttp://www.sec.gov/CIK0000715579duration2013-01-01T00:00:002013-06-30T00:00:001true 3us-gaap_GuaranteeObligationsLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Guarantor Obligations [Line Items]2false 4acnb_LineofCreditFacilityExpirationPeriodacnb_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse001 yearfalsefalsefalsexbrli:durationItemTypenaLine of Credit Facility, Expiration PeriodNo definition available.false0Line of credit facility expiration period3false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false USDtruefalse$I2013Q2_us-gaap_GuaranteeObligationsByNatureAxis_us-gaap_StandbyLettersOfCreditMemberhttp://www.sec.gov/CIK0000715579instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseStandby Letters of Credit [Member]us-gaap_GuaranteeObligationsByNatureAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_StandbyLettersOfCreditMemberus-gaap_GuaranteeObligationsByNatureAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Standby Letters of Credit [Member]4true 3us-gaap_GuaranteeObligationsLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Guarantor Obligations [Line Items]5false 4us-gaap_GuaranteesFairValueDisclosureus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse43010004301USD$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 item represents the amount of contractual guarantees to which the Company is obligated as of the balance sheet date.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12201-110248 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 45 -Paragraph 3, 8, 15 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Guarantees amountfalseGuarantees (Narrative) (Details) (USD $)ThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.acnb.com/role/GuaranteesNarrativeDetails15