2.2.0.25falsefalse41902 - Disclosure - Acquisition of XTO Energy Inc. (Components of Consideration Transferred in Merger of XTO Energy Inc.) (Details)truefalseIn Millions, except Per Share datafalse1falsefalseUSDfalsefalse6/1/2010 - 6/25/2010
USD ($)
USD ($) / shares
$Duration_6_1_2010_To_6_25_2010http://www.sec.gov/CIK0000034088duration2010-06-01T00:00:002010-06-25T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit14Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit13Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse12/31/2010
USD ($)
USD ($) / shares
$As_Of_12_31_2010http://www.sec.gov/CIK0000034088instant2010-12-31T00:00:000001-01-01T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit13Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit14Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$5false0us-gaap_BusinessAcquisitionCostOfAcquiredEntityEquityInterestsIssuedAndIssuableus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse2448000000024480[1],[2]falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe acquisition-date fair value of the equity interests of the acquirer, including the number of instruments or interests issued or issuable in consideration for the business combination.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-Subparagraph f(4)
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 88-16
Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 51
-Subparagraph d
Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 39
falsefalse6false0xom_BusinessAcquisitionCostOfAcquiredEntityEquityInterestsIssuedAndIssuableShareBasedAwardsxomfalsedebitinstantBusiness Acquisition Cost Of Acquired Entity Equity Interests Issued And Issuable Share Based Awardsfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse179000000179[2]falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryBusiness Acquisition Cost Of Acquired Entity Equity Interests Issued And Issuable Share Based AwardsNo authoritative reference available.falsefalse7false0us-gaap_BusinessCombinationConsiderationTransferredus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse2465900000024659falsefalsefalsefalsefalse2truefalsefalse2465900000024659falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis element represents the acquisition-date fair value of the total consideration transferred which consists of the sum of the acquisition-date fair values of the assets transferred by the acquirer, the liabilities incurred by the acquirer to former owners of the acquiree, and the equity interests issued by the acquirer.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 39, 40
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-Subparagraph f
truefalse8false0xom_CommonStockFairMarketValuePriceAtAcquisitionDatexomfalsenadurationCommon Stock Fair Market Value Price At Acquisition Datefalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse59.1059.10falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseEPSus-types:perShareItemTypedecimalCommon Stock Fair Market Value Price At Acquisition DateNo authoritative reference available.falsetrue9false0xom_SharesOfTreasuryStockIssuedForAcquisitionxomfalsenadurationShares Of Treasury Stock Issued For Acquisitionfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse416000000416falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseSharesxbrli:sharesItemTypesharesShares Of Treasury Stock Issued For AcquisitionNo authoritative reference available.falsefalse10false0xom_CostOfTreasurySharesIssuedForAcquisitionxomfalsedebitdurationCost Of Treasury Shares Issued For Acquisitionfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse2113900000021139falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryCost Of Treasury Shares Issued For AcquisitionNo authoritative reference available.falsefalse11false0xom_ExcessFairValueOverCostOfTreasuryStockIssuedUsedInAcquisitionxomfalsedebitdurationExcess Fair Value Over Cost Of Treasury Stock Issued Used In Acquisitionfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse35200000003520falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryExcess Fair Value Over Cost Of Treasury Stock Issued Used In AcquisitionNo authoritative reference available.falsefalse1The fair value of the Corporation's common stock on the acquisition date was $59.10 per share based on the closing value on the NYSE. The Corporation issued 416 million shares of stock previously held in treasury. The treasury stock issued, based on the average cost, was valued at $21,139 million. The excess of the fair value of the consideration transferred over the cost of treasury stock issued was $3,520 million and was included in common stock without par value. 2The portion of the fair value of XTO converted stock-based awards attributable to pre-merger employee service was part of consideration. The remaining fair value of the awards will be recognized in future periods over the requisite service period. 27Acquisition of XTO Energy Inc. (Components of Consideration Transferred in Merger of XTO Energy Inc.) (Details) (USD $)MillionsMillionsNoRoundingUnKnownfalsetrue
