Joint Venture Acquisition Obligation (Details) (USD $)	9 Months Ended
Sep. 30, 2013
Joint Venture Acquisition Obligation (Textual) [Abstract]
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	803,000,000
Principal payment for joint venture obligation	$ 575,000,000
Fixed-rate on joint venture acquisition obligation	5.30%
Percentage of quarterly interest payment as capital contribution	50.00%

Fixed annual interest rate on joint venture acquisition obligation.

No definition available.

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Obligation to Joint Venture over a 10-year period, beginning in 2007.

No definition available.

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Amount of the required quarterly payments applied to principal.

No definition available.

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Amount of the required quarterly payments including both interest and principal payments for Joint Venture Acquisition Obligation.

No definition available.

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Percent of the quarterly interest payment that is reflected as a capital contribution.

No definition available.

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Short-term portion of principal obligation amount.

No definition available.

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Time period for contribution.

No definition available.

Name:	cop_TimePeriodForContribution
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