2.2.0.25truefalse41201 - Disclosure - Financial Instruments and Derivatives (Narrative) (Details)truefalsefalse1falsefalseUSDfalsefalse1/1/2010 - 12/31/2010
USD ($)
USD ($) / shares
$Duration_1_1_2010_To_12_31_2010http://www.sec.gov/CIK0000034088duration2010-01-01T00:00:002010-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit14Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit13Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit15Standardhttp://xbrl.us/us-types/2009-01-31cubicFeetxbrlus0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2009 - 12/31/2009
USD ($)
USD ($) / shares
$Duration_1_1_2009_To_12_31_2009http://www.sec.gov/CIK0000034088duration2009-01-01T00:00:002009-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit14Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3falsefalseUSDfalsefalse1/1/2008 - 12/31/2008
USD ($)
USD ($) / shares
$Duration_1_1_2008_To_12_31_2008http://www.sec.gov/CIK0000034088duration2008-01-01T00:00:002008-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit14Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$2false0us-gaap_DebtInstrumentFairValueus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse1280000000012800000000falsetruefalsefalsefalse2truefalsefalse77000000007700000000falsetruefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryEstimated fair value of the debt instrument at the balance-sheet date.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
falsefalse3false0us-gaap_LongTermDebtAndCapitalLeaseObligationsus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse1222700000012227000000falsefalsefalsefalsefalse2truefalsefalse71290000007129000000falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetarySum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year or the normal operating cycle, if longer plus capital lease obligations due to be paid more than one year after the balance sheet date.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section H
falsefalse4false0xom_DerivativeAssetsAtFairValueNetxomfalsedebitinstantDerivative Assets At Fair Value Netfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse172000000172000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryDerivative Assets At Fair Value NetNo authoritative reference available.falsefalse5false0xom_DerivativeLiabilitiesAtFairValueNetxomfalsecreditinstantDerivative Liabilities At Fair Value Netfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse50000005000000falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryDerivative Liabilities At Fair Value NetNo authoritative reference available.falsefalse6false0xom_DerivativeInstrumentsNetAssetBalanceAcquiredAsResultOfXtoMergerxomfalsedebitinstantDerivative Instruments Net Asset Balance Acquired as a Result of XTO Mergerfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse219000000219000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryDerivative Instruments Net Asset Balance Acquired as a Result of XTO MergerNo authoritative reference available.falsefalse7false0us-gaap_GainLossOnDerivativeInstrumentsNetPretaxus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse221000000221000000falsefalsefalsefalsefalse2truefalsefalse-73000000-73000000falsefalsefalsefalsefalse3truefalsefalse154000000154000000falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.No authoritative reference available.falsefalse8false0xom_VolumeMillionsOfCubicFeetDailyxomfalsenadurationNotional daily commodity volume associated with the derivative contracts expressed in millions of cubic feet daily for...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse250250falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseOtherus-types:volumeItemTypedecimalNotional daily commodity volume associated with the derivative contracts expressed in millions of cubic feet daily for natural gas and thousands of barrels daily for crude oil.No authoritative reference available.falsefalse9false0xom_WeightedAverageNymexPricePerThousandCubicFeetxomfalsenadurationUnderlying fixed price per unit to be received in exchange for the market price on the derivative settlement date.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse7.027.02falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseEPSus-types:perUnitItemTypedecimalUnderlying fixed price per unit to be received in exchange for the market price on the derivative settlement date.No authoritative reference available.falsetrue10false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://www.exxonmobil.com/taxonomy/role/disclosurefinancialinstrumentsandderivativesnarrativedetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalseUSDtruefalse{us-gaap_DerivativesFairValueByDerivativeInstrumentRiskAxis} : Cash Flow Hedge [Member]
1/1/2010 - 12/31/2010
USD ($)
$Duration_1_1_2010_To_12_31_20103374http://www.sec.gov/CIK0000034088duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseCash Flow Hedge [Member]us-gaap_DerivativesFairValueByDerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_CashFlowHedgingMemberus-gaap_DerivativesFairValueByDerivativeInstrumentRiskAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalse11false0us-gaap_GainLossOnDerivativeInstrumentsNetPretaxus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse218000000218000000falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.No authoritative reference available.falsefalse310Financial Instruments and Derivatives (Narrative) (Details) (USD $)NoRoundingUnKnownNoRoundingUnKnowntruetrue
