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