v2.4.0.8

Fair Value Measurement (Details Textual) | Jun. 30, 2013 | Dec. 31, 2012
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Reported Fair Values of Financial Instruments (Textual) [Abstract] |  |
Effective yield rate | 0.81% | 0.70%

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- Definition Effective yield rate. + References No definition available. + Details
Name: | cop_EffectiveYieldRate
Namespace Prefix: | cop_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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