2.4.0.8091100 - Disclosure - SUBSEQUENT EVENTS (Details)truefalseIn Millions, except Share data, unless otherwise specifiedfalse1false USDfalsefalse$c20130701to20130730_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_WaterMillAndMiddleIslandBranchClosingsMember_SubsequentEventTypeAxis_SubsequentEventMemberhttp://www.sec.gov/CIK0000754673duration2013-07-01T00:00:002013-07-30T00:00:00U002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse1false USDtruefalse$c20130701to20130730_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_WaterMillAndMiddleIslandBranchClosingsMember_SubsequentEventTypeAxis_SubsequentEventMemberhttp://www.sec.gov/CIK0000754673duration2013-07-01T00:00:002013-07-30T00:00:00falsefalseSubsequent Event [Member]us-gaap_SubsequentEventTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_SubsequentEventMemberus-gaap_SubsequentEventTypeAxisexplicitMemberfalsefalseWater Mill and Middle Island Branch Closings [Member]us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxisxbrldihttp://xbrl.org/2006/xbrldisubk_WaterMillAndMiddleIslandBranchClosingsMemberus-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxisexplicitMemberU002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Water Mill and Middle Island Branch Closings [Member]2true 3us-gaap_SubsequentEventLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Subsequent Event [Line Items]3false 4us-gaap_RestructuringChargesus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse6000000.6USD$falsetruefalsexbrli:monetaryItemTypemonetaryAmount charged against earnings in the period for incurred and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding asset retirement obligations.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB TOPIC 5.P.4(b)) -URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140904-122747 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.P.3) -URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140864-122747 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section P -Subsection 3, 4 false2One-time pretax charge associated with closure of bank branches4false 4subk_EffectOnFutureOperatingExpensessubk_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse8000000.8USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe anticipated reduction in future operating expenses associated with the closure of the branches.No definition available.false2Anticipated reduction in annual operating expenses from the closure5false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false USDtruefalse$c20130730_SaleAxis_OwnerOfVisaClassBStockMember_SubsequentEventTypeAxis_SubsequentEventMemberhttp://www.sec.gov/CIK0000754673instant2013-07-30T00:00:000001-01-01T00:00:00falsefalseSubsequent Event [Member]us-gaap_SubsequentEventTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_SubsequentEventMemberus-gaap_SubsequentEventTypeAxisexplicitMemberfalsefalseOwner of Visa Class B Stock [Member]us-gaap_SaleAxisxbrldihttp://xbrl.org/2006/xbrldisubk_OwnerOfVisaClassBStockMemberus-gaap_SaleAxisexplicitMemberU001Standardhttp://www.xbrl.org/2003/instancesharesxbrli0U004Standardhttp://www.xbrl.org/2003/instancepurexbrli0U002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Owner of Visa Class B Stock [Member]6true 3us-gaap_SubsequentEventLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Subsequent Event [Line Items]7false 4subk_PercentageOfSharesIssuedSubsequentlyRedeemedInInitialPublicOfferingsubk_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.390.39falsefalsefalsenum:percentItemTypepureRepresents the percentage of the Visa Class B shares issued to Company that were subsequently redeemed in initial public offering (IPO).No definition available.false0Percentage of shares issued subsequently redeemed in initial public offering (in hundredths)8false 4subk_SharesOfStockSoldInStockTransactionsubk_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse5000050000falsefalsefalsexbrli:sharesItemTypesharesThe number of shares sold by the Company in stock transaction.No definition available.false1Shares of stock sold in stock transaction (in shares)9false 4subk_GainOnSaleOfClassBStocksubk_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse38000003.8USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe difference between the carrying value and the sale price of an investment. A gain would be recognized when the sale price of the investment is greater than the carrying value of the investment.No definition available.false2Pre-tax gain on the sale of Class B stock10false 4subk_AccruedLiabilityFromSaleOfClassBStocksubk_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse5000000.5USD$falsetruefalsexbrli:monetaryItemTypemonetaryRepresents the amount of liability accrued by Company for the retained risk of future additions to Visa litigation reserve.No definition available.false2Accrued liability from sale of Class B stock11false 4subk_SaleOfStockOwnershipAfterTransactionsubk_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse8863888638falsefalsefalsexbrli:sharesItemTypesharesNumber of Class B stock owned by Company after stock transaction.No definition available.false1Shares of stock owned by Company after sale of stock (in shares)falseSUBSEQUENT EVENTS (Details) (Subsequent Event [Member], USD $)HundredThousandsNoRoundingUnKnownUnKnowntruefalsefalseSheethttp://suffolkbancorp.com/role/SubsequentEventsDetails111