v2.4.0.6

Non-Mineral Leases - Future Minimum Rental Payments Due under Noncancelable Leases (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2011
--- | ---
Operating Leased Assets [Line Items] |
Railcars subleased to CPChem, a related Party | $ 64

X
- Definition Income from sublease of railcars to related party. + References No definition available. + Details
Name: | cop_IncomeFromSubleaseOfRailcarsToRelatedParty
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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