2.2.0.25truefalse1750 - Disclosure - Stockholders' Equity - Additional Information (Detail)truefalsefalse1falsefalseUSDfalsefalse5/1/2009 - 5/31/2009 USD ($) $FROM_May01_2009_TO_May31_2009http://www.sec.gov/CIK0000773910duration2009-05-01T00:00:002009-05-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0usdPerShrDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2010 - 12/31/2010 USD ($) / shares USD ($) $FROM_Jan01_2010_TO_Dec31_2010http://www.sec.gov/CIK0000773910duration2010-01-01T00:00:002010-12-31T00:00:00usdPerShrDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0MMboeStandardhttp://www.anadarko.com/20101231MMboeapc0BcfStandardhttp://www.anadarko.com/20101231Bcfapc0USDUSD$3falsefalseUSDfalsefalse1/1/2009 - 12/31/2009 USD ($) USD ($) / shares $FROM_Jan01_2009_TO_Dec31_2009http://www.sec.gov/CIK0000773910duration2009-01-01T00:00:002009-12-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170usdPerShrDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0MMboeStandardhttp://www.anadarko.com/20101231MMboeapc0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0BcfStandardhttp://www.anadarko.com/20101231Bcfapc0USDUSD$4falsefalseUSDfalsefalse1/1/2008 - 12/31/2008 USD ($) USD ($) / shares $FROM_Jan01_2008_TO_Dec31_2008http://www.sec.gov/CIK0000773910duration2008-01-01T00:00:002008-12-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0MMboeStandardhttp://www.anadarko.com/20101231MMboeapc0usdPerShrDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$5falsefalseUSDtruefalse{us-gaap_StatementClassOfStockAxis} : Series B 5 Point 46 Percent Cumulative Preferred Stock [Member] 1/1/2008 - 12/31/2008 USD ($) / shares $FROM_Jan01_2008_TO_Dec31_2008_us-gaap_StatementClassOfStockAxis_SeriesB5Point46PercentCumulativePreferredStockMemberhttp://www.sec.gov/CIK0000773910duration2008-01-01T00:00:002008-12-31T00:00:00falsefalseSeries B 5 Point 46 Percent Cumulative Preferred Stock [Member]us-gaap_StatementClassOfStockAxisxbrldihttp://xbrl.org/2006/xbrldiapc_SeriesB5Point46PercentCumulativePreferredStockMemberus-gaap_StatementClassOfStockAxisexplicitMemberusdPerShrDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$6falsefalseUSDtruefalse{us-gaap_StatementClassOfStockAxis} : Series B 5 Point 46 Percent Cumulative Preferred Stock [Member] 6/30/2008 USD ($) $AS_OF_Jun30_2008_us-gaap_StatementClassOfStockAxis_SeriesB5Point46PercentCumulativePreferredStockMemberhttp://www.sec.gov/CIK0000773910instant2008-06-30T00:00:000001-01-01T00:00:00falsefalseSeries B 5 Point 46 Percent Cumulative Preferred Stock [Member]us-gaap_StatementClassOfStockAxisxbrldihttp://xbrl.org/2006/xbrldiapc_SeriesB5Point46PercentCumulativePreferredStockMemberus-gaap_StatementClassOfStockAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$7falsefalsetruefalse{apc_ShareRepurchaseProgramAxis} : Five Billion Dollar Share-repurchase Program [Member] 1/1/2010 - 12/31/2010 FROM_Jan01_2010_TO_Dec31_2010_apc_ShareRepurchaseProgramAxis_FiveBillionDollarShareRepurchaseProgramMemberhttp://www.sec.gov/CIK0000773910duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseFive Billion Dollar Share-repurchase Program [Member]apc_ShareRepurchaseProgramAxisxbrldihttp://xbrl.org/2006/xbrldiapc_FiveBillionDollarShareRepurchaseProgramMemberapc_ShareRepurchaseProgramAxisexplicitMemberSharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli08falsefalsetruefalse{apc_ShareRepurchaseProgramAxis} : Five Billion Dollar Share-repurchase Program [Member] 1/1/2009 - 12/31/2009 FROM_Jan01_2009_TO_Dec31_2009_apc_ShareRepurchaseProgramAxis_FiveBillionDollarShareRepurchaseProgramMemberhttp://www.sec.gov/CIK0000773910duration2009-01-01T00:00:002009-12-31T00:00:00falsefalseFive Billion Dollar Share-repurchase Program [Member]apc_ShareRepurchaseProgramAxisxbrldihttp://xbrl.org/2006/xbrldiapc_FiveBillionDollarShareRepurchaseProgramMemberapc_ShareRepurchaseProgramAxisexplicitMemberSharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli09falsefalseUSDtruefalse{apc_ShareRepurchaseProgramAxis} : Five Billion Dollar Share-repurchase Program [Member] 1/1/2008 - 12/31/2008 USD ($) $FROM_Jan01_2008_TO_Dec31_2008_apc_ShareRepurchaseProgramAxis_FiveBillionDollarShareRepurchaseProgramMemberhttp://www.sec.gov/CIK0000773910duration2008-01-01T00:00:002008-12-31T00:00:00falsefalseFive Billion Dollar Share-repurchase Program [Member]apc_ShareRepurchaseProgramAxisxbrldihttp://xbrl.org/2006/xbrldiapc_FiveBillionDollarShareRepurchaseProgramMemberapc_ShareRepurchaseProgramAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$10falsefalseUSDtruefalse{apc_ShareRepurchaseProgramAxis} : Five Billion Dollar Share-repurchase Program [Member] 8/31/2008 USD ($) $AS_OF_Aug31_2008_apc_ShareRepurchaseProgramAxis_FiveBillionDollarShareRepurchaseProgramMemberhttp://www.sec.gov/CIK0000773910instant2008-08-31T00:00:000001-01-01T00:00:00falsefalseFive Billion Dollar Share-repurchase Program [Member]apc_ShareRepurchaseProgramAxisxbrldihttp://xbrl.org/2006/xbrldiapc_FiveBillionDollarShareRepurchaseProgramMemberapc_ShareRepurchaseProgramAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false0apc_ShareRepurchaseProgramAuthorizedAllocationOfAmountapcfalsedebitinstantShare-repurchase program, authorized allocation of amountfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10truefalsefalse50000000005000000000falsetruefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryShare-repurchase program, authorized allocation of amountNo authoritative reference available.falsefalseShare-repurchase program, authorized allocation amount3false0us-gaap_TreasuryStockSharesAcquiredus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4truefalsefalse1000000010000000falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7truefalsefalse00falsefalsefalsetruefalse8truefalsefalse00falsefalsefalsetruefalse9truefalsefalse1000000010000000falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseSharesxbrli:sharesItemTypesharesNumber of shares that have been repurchased during the period and are being held in treasury.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 falsefalsePurchase of treasury stock4false0us-gaap_PaymentsForRepurchaseOfCommonStockus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse4200000042000000falsefalsefalsefalsefalse3truefalsefalse3500000035000000falsefalsefalsefalsefalse4truefalsefalse631000000631000000falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9truefalsefalse600000000600000000falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow to reacquire common stock during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a falsefalsePayments for repurchase of common stock5false0us-gaap_StockIssuedDuringPeriodSharesNewIssuesus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse3000000030000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3truefalsefalse3000000030000000falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseSharesxbrli:sharesItemTypesharesNumber of new stock issued during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 falsefalseIssuance of common stock6false0apc_IssuanceOfCommonStockPricePerShareapcfalsenainstantIssuance of common stock, price per sharefalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse45.5045.50falsetruefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseEPSus-types:perShareItemTypedecimalIssuance of common stock, price per shareNo authoritative reference available.falsetrueIssuance of common stock, price per share7false0us-gaap_PaymentOfFinancingAndStockIssuanceCostsus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse2800000028000000falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThe total of the cash outflow during the period which has been paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt and the cost incurred directly for the issuance of equity securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18, 19, 20 falsefalseStock issuance costs8false0us-gaap_ProceedsFromIssuanceOfCommonStockus-gaaptruedebitdurationNo definition available.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:monetaryItemTypemonetaryThe cash inflow from the additional capital contribution to the entity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph a falsefalseProceeds from issuance of common stock, net of underwriting discount and other offering costs9false0apc_NumberOfSharesHeldByExecutivesAndDirectorsBenefitsTrustapcfalsenainstantNumber of shares held by the Anadarko Petroleum Corporation Executives and Directors Benefits Trust.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse40000004000000falsefalsefalsefalsefalse3truefalsefalse40000004000000falsefalsefalsefalsefalse4truefalsefalse40000004000000falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseSharesxbrli:sharesItemTypesharesNumber of shares held by the Anadarko Petroleum Corporation Executives and Directors Benefits Trust.No authoritative reference available.falsefalseNumber of shares held by Anadarko Petroleum Corporation Executives and Directors Benefits Trust10false0us-gaap_PreferredStockRedemptionAmountus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsetruefalse6truefalsefalse4500000045000000falsetruefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThe redemption (or callable) amount of currently redeemable preferred stock. Includes amounts representing dividends not currently declared or paid but which will be payable under the redemption features or for which ultimate payment is solely within the control of the issuer.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 8 falsefalseRedemption amount of preferred stock11false0apc_AnnualRateOfCumulativeCashDividendsPerShareapcfalsenadurationAnnual rate of cumulative cash dividends per sharefalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5truefalsefalse5.465.46falsetruefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseEPSus-types:perShareItemTypedecimalAnnual rate of cumulative cash dividends per shareNo authoritative reference available.falsetrueAnnual rate of cumulative cash dividends per share12false0apc_PreferredStockDividendsPerShareCashPaidapcfalsenadurationAggregate dividends paid during the period for each share of preferred stock outstanding.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5truefalsefalse27.3027.30falsetruefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseEPSus-types:perShareItemTypedecimalAggregate dividends paid during the period for each share of preferred stock outstanding.No authoritative reference available.falsetruePreferred stock dividends per share paid13false0apc_PreferredStockDividendsPerDepositaryShareCashPaidapcfalsenadurationAggregate preferred stock dividends paid during the period for each Depositary Share.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5truefalsefalse2.732.73falsetruefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalse9falsefalsefalse00falsefalsefalsetruefalse10falsefalsefalse00falsefalsefalsetruefalseEPSus-types:perShareItemTypedecimalAggregate preferred stock dividends paid during the period for each Depositary Share.No authoritative reference available.falsetruePreferred stock dividends per Depositary Share paid1012Stockholders' Equity - Additional Information (Detail) (USD $)NoRoundingNoRoundingUnKnownUnKnownfalsetrue