v2.4.0.6

Joint Venture Acquisition Obligation - Additional Information (Detail) (USD $) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2011 | Dec. 31, 2011 | Dec. 31, 2007
Related Party Transaction [Line Items] |  |  |
Initial acquisition obligation to joint venture |  |  | $ 7,500,000,000
Time period for contribution |  |  | 10 years
Quarterly principal and interest payments for joint venture acquisition obligation |  | 237,000,000 |
Short-term portion of principal obligation amount | 732,000,000 | 732,000,000 |
Principal payment for joint venture obligation |  | $ 695,000,000 |
Fixed-rate on joint venture acquisition obligation |  | 5.30% |
Percentage of quarterly interest payment as capital contribution | 50.00% |  |

X
- Definition Fixed annual interest rate on joint venture acquisition obligation. + References No definition available. + Details
Name: | cop_FixedAnnualInterestRateOnJointVentureAcquisitionObligation
Namespace Prefix: | cop_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Obligation to Joint Venture over a 10-year period, beginning in 2007. + References No definition available. + Details
Name: | cop_InitialAcquisitionObligationToJointVenture
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of the required quarterly payments applied to principal. + References No definition available. + Details
Name: | cop_JointVentureAcquisitionObligationPrincipalPayment
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of the required quarterly payments including both interest and principal payments for Joint Venture Acquisition Obligation. + References No definition available. + Details
Name: | cop_JointVentureAcquisitionObligationQuarterlyPayment
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percent of the quarterly interest payment that is reflected as a capital contribution. + References No definition available. + Details
Name: | cop_PercentOfQuarterlyInterestPaymentAsCapitalContribution
Namespace Prefix: | cop_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Short-term portion of principal obligation amount. + References No definition available. + Details
Name: | cop_ShortTermPortionOfPrincipalObligationAmount
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Time period for contribution. + References No definition available. + Details
Name: | cop_TimePeriodForContribution
Namespace Prefix: | cop_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration