v2.4.0.6

Related Party Transactions - Significant Transactions with Related Parties (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
Related Party Transaction [Line Items] |  |  |  |
Discontinued operations, Revenue from related parties | $ 8,304 | $ 7,315 |  | $ 7,184
Before-tax gain from sale to DCP Midstream |  | 1,149 | [1] |
Before-tax gain on sale of LUKOIL shares under a stock purchase and option agreement with a wholly owned subsidiary |  | 1,149 |  |
Discontinued operations, Purchases from related parties | 20,369 | 15,163 |  | 11,965
Discontinued operations, Expenses from transactions with related parties | 159 | 106 |  | 93
Discontinued operations, Interest expense | 10 |  |  |
Discontinued operations, Interest income |  | 2 |  | 10
Seaway Products Pipeline [Member] |  |  |  |
Related Party Transaction [Line Items] |  |  |  |
Proceeds from Sale of Oil and Gas Property and Equipment | 400 |  |  |
Before-tax gain from sale to DCP Midstream | $ 156 |  |  |
[1] | In 2011, we sold the Seaway Products Pipeline to DCP Midstream for cash proceeds of $400 million, resulting in a before-tax gain of $156 million, which is included in discontinued operations and excluded from the table above. During 2010, we sold a portion of our LUKOIL shares under a stock purchase and option agreement with a wholly owned subsidiary of LUKOIL, resulting in a before-tax gain of $1,149 million.

X
- Definition Discontinued Operations Interest Expense Related Party + References No definition available. + Details
Name: | cop_DiscontinuedOperationsInterestExpenseRelatedParty
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Discontinued Operations Interest Income Related Party + References No definition available. + Details
Name: | cop_DiscontinuedOperationsInterestIncomeRelatedParty
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Discontinued Operations Related Party Transaction Expenses From Transactions With Related Party + References No definition available. + Details
Name: | cop_DiscontinuedOperationsRelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Discontinued Operations Related Party Transaction Purchases From Related Parties + References No definition available. + Details
Name: | cop_DiscontinuedOperationsRelatedPartyTransactionPurchasesFromRelatedParties
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Discontinued Operations Revenue From Related Parties + References No definition available. + Details
Name: | cop_DiscontinuedOperationsRevenueFromRelatedParties
Namespace Prefix: | cop_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the amount of gain (loss) arising from the disposal of an equity method investment. + References No definition available. + Details
Name: | us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Gain (loss) on entity's disposition of equity in securities of subsidiaries. Reflects the difference in the parent company's carrying amount of the equity interest in the subsidiary immediately before and after all stock transactions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 13 -Subparagraph g -Article 9 + Details
Name: | us-gaap_GainOrLossOnSaleOfStockInSubsidiary
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph c -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. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 -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. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfOilAndGasPropertyAndEquipment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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