v2.4.0.6

Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2009
Accounting Policies [Line Items] |
Excess of amount paid for redemption of noncontrolling interest over its carrying value | $ 12

X
- Details
Name: | cop_AccountingPoliciesLineItems
Namespace Prefix: | cop_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Excess of amount paid for redemption of noncontrolling interest over its carrying value. + References No definition available. + Details
Name: | cop_ExcessOfAmountPaidForRedemptionOfNoncontrollingInterestOverItsCarryingValue
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration