2.2.0.25truefalse1873 - Disclosure - Contingencies - Deepwater Royalty Relief Act (Detail)truefalseIn Millionsfalse1falsefalseUSDfalsefalse1/1/2009 - 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/instancesharesxbrli0USDUSD$2falsefalseUSDtruefalse{us-gaap_LossContingenciesByNatureOfContingencyAxis} : Deepwater Royalty Relief Act [Member] 1/1/2009 - 12/31/2009 USD ($) $FROM_Jan01_2009_TO_Dec31_2009_us-gaap_LossContingenciesByNatureOfContingencyAxis_DeepwaterRoyaltyReliefActMemberhttp://www.sec.gov/CIK0000773910duration2009-01-01T00:00:002009-12-31T00:00:00falsefalseDeepwater Royalty Relief Act [Member]us-gaap_LossContingenciesByNatureOfContingencyAxisxbrldihttp://xbrl.org/2006/xbrldiapc_DeepwaterRoyaltyReliefActMemberus-gaap_LossContingenciesByNatureOfContingencyAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3falsefalseUSDtruefalse{us-gaap_LossContingenciesByNatureOfContingencyAxis} : Deepwater Royalty Relief Act [Member] 9/30/2009 USD ($) $AS_OF_Sep30_2009_us-gaap_LossContingenciesByNatureOfContingencyAxis_DeepwaterRoyaltyReliefActMemberhttp://www.sec.gov/CIK0000773910instant2009-09-30T00:00:000001-01-01T00:00:00falsefalseDeepwater Royalty Relief Act [Member]us-gaap_LossContingenciesByNatureOfContingencyAxisxbrldihttp://xbrl.org/2006/xbrldiapc_DeepwaterRoyaltyReliefActMemberus-gaap_LossContingenciesByNatureOfContingencyAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false0apc_ReversalOfAccrualForDeepwaterRoyaltyReliefActDisputeapcfalsecreditdurationReversal of accrued liability for royalties related to Deepwater Royalty Relief Act dispute.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse657000000657falsetruefalsefalsefalse2truefalsefalse657000000657falsetruefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryReversal of accrued liability for royalties related to Deepwater Royalty Relief Act dispute.No authoritative reference available.falsefalseReversal of accrual for Deepwater Royalty Relief Act dispute3false0us-gaap_AccruedRoyaltiesCurrentAndNoncurrentus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3truefalsefalse657000000657falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryCarrying value as of the balance sheet date of obligations incurred through that date and payable for royalties.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 15 -Subparagraph 5 -Article 9 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 15 -Subparagraph a -Article 7 falsefalseAccrued royalties4false0us-gaap_BusinessAcquisitionPreacquisitionContingencyAmountus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsetruefalse3truefalsefalse165000000165falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryAmount assigned in the purchase price allocation to the preacquisition contingency.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 141 -Paragraph 40, 41 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 2 -Section A -Subsection 7 falsefalseLiability related to pre-acquisition contingencies recorded in purchase accounting5false0apc_UnpaidInterestExpenseReversalapcfalsecreditdurationUnpaid interest expense reversalfalsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse7800000078falsetruefalsetruefalse3falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryUnpaid interest expense reversalNo authoritative reference available.falsefalseUnpaid Interest Expense Reversal34Contingencies - Deepwater Royalty Relief Act (Detail) (USD $)MillionsUnKnownUnKnownUnKnownfalsetrue