2.2.0.25falsefalse41901 - Disclosure - Acquisition of XTO Energy Inc. (Narrative) (Details)truefalseIn Millions, unless otherwise specifiedfalse1falsefalseUSDfalsefalse1/1/2010 - 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$5false0us-gaap_BusinessAcquisitionEffectiveDateOfAcquisitionus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse002010/06/252010/06/25falsefalsefalsefalsefalseOtherus-types:dateStringItemTypenormalizedstringMonth, date and year when the results of operations of the acquired entity began to be included in the income statement of the combined entity. For disclosure purposes, the effective date of an acquisition equates to the acquisition date, when acquisition date is defined as the date on which the acquirer obtained control of the acquired entity. The effective date of an acquisition may be either earlier or later than the date on which the acquisition agreement was executed (closed).Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 10, 11
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 3
-Subparagraph c
Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-Subparagraph b
falsefalse6false0xom_ShareExchangeRatioAcquisitionxomfalsenadurationShare Exchange Ratio Acquisitionfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse0.70980.7098falsefalsefalsefalsefalseOtherxbrli:decimalItemTypedecimalShare Exchange Ratio AcquisitionNo authoritative reference available.falsefalse7false0us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCostsus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse1800000018falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAmount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 51
-Subparagraph d
Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 24
falsefalse13Acquisition of XTO Energy Inc. (Narrative) (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruetrue
