v2.4.0.6

Goodwill and Intangibles - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2011 | Dec. 31, 2010
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Goodwill And Intangible Assets [Line Items] |  |
Amortized intangible asset | $ 44 | $ 62

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

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- Definition Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16323-109275 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 45 -Subparagraph a(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | debit
Period Type: | instant