2.2.0.25falsefalse40902 - Disclosure - Accounting for Suspended Exploratory Well Costs (Change in Capitalized Suspended Exploratory Well Costs) (Details)truefalseIn Millionsfalse1falsefalseUSDfalsefalse1/1/2010 - 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$5false0us-gaap_CapitalizedExploratoryWellCostsus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsetruefalsefalseperiodstartlabel1truefalsefalse20050000002005falsetruefalsefalsefalse2truefalsefalse15850000001585falsetruefalsefalsefalse3truefalsefalse12910000001291falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of capitalized exploratory well costs that is pending the determination of proved reserves. This should not include amounts that were capitalized and subsequently expensed in the same annual period.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS19-1
-Paragraph 10
-Subparagraph a
falsefalse6false0us-gaap_CapitalizedExploratoryWellCostAdditionsPendingDeterminationOfProvedReservesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse11030000001103falsefalsefalsefalsefalse2truefalsefalse624000000624falsefalsefalsefalsefalse3truefalsefalse448000000448falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAdditions to capitalized exploratory well costs that were added during the reporting period pending the determination of proved reserves.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS19-1
-Paragraph 10
-Subparagraph a
falsefalse7false0us-gaap_CapitalizedExploratoryWellCostChargedToExpenseus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse-104000000-104falsefalsefalsefalsefalse2truefalsefalse-51000000-51falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryCapitalized exploratory well costs that were expensed during the year because proved reserves were not found at the exploratory well.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS19-1
-Paragraph 10
-Subparagraph a
falsefalse8false0us-gaap_ReclassificationToWellFacilitiesAndEquipmentBasedOnDeterminationOfProvedReservesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse-136000000-136falsefalsefalsefalsefalse2truefalsefalse-200000000-200falsefalsefalsefalsefalse3truefalsefalse-101000000-101falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryPreviously capitalized costs of the drilling of wells that were reclassified as part of the costs of the enterprise's wells and related equipment and facilities at the time that proved reserves were found.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS19-1
-Paragraph 10
-Subparagraph a
falsefalse9false0xom_OtherCapitalizedExploratoryWellCostsxomfalsedebitinstantOther Capitalized Exploratory Well Costsfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse2500000025falsefalsefalsefalsefalse2truefalsefalse4700000047falsefalsefalsefalsefalse3truefalsefalse-53000000-53falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryOther Capitalized Exploratory Well CostsNo authoritative reference available.falsefalse10false0us-gaap_CapitalizedExploratoryWellCostsus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsetruefalseperiodendlabel1truefalsefalse28930000002893falsefalsefalsefalsefalse2truefalsefalse20050000002005falsefalsefalsefalsefalse3truefalsefalse15850000001585falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of capitalized exploratory well costs that is pending the determination of proved reserves. This should not include amounts that were capitalized and subsequently expensed in the same annual period.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS19-1
-Paragraph 10
-Subparagraph a
falsefalse11false0xom_CapitalizedExploratoryWellCostsAttributableToEquityCompaniesxomfalsedebitinstantCapitalized Exploratory Well Costs Attributable To Equity Companiesfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse90000009falsetruefalsefalsefalse3truefalsefalse1000000010falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryCapitalized Exploratory Well Costs Attributable To Equity CompaniesNo authoritative reference available.falsefalse37Accounting for Suspended Exploratory Well Costs (Change in Capitalized Suspended Exploratory Well Costs) (Details) (USD $)MillionsUnKnownUnKnownUnKnownfalsetrue
