Cash outflow related to foreigh currecy transaction for derivatives.

No definition available.

Name:	cop_PaymentsForForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments
Namespace Prefix:	cop_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash received for the settlement of litigation during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3536-108585

+ Details

Name:	us-gaap_ProceedsFromLegalSettlements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	srt_LitigationCaseAxis=cop_BurlingtonResourcesIncVsTheRepublicOfEcuadorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=cop_ConocoPhillipsVsPetroleosDeVenezuelaSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CurrencySwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Cash Flow Information - Textual (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2017
Burlington Resources Inc Vs The Republic Of Ecuador [Member]
Loss Contingencies [Line Items]
Cash Proceeds from Legal Settlements		$ 262
Conoco Phillips Vs Petroleos de Venezuela SA [Member]
Loss Contingencies [Line Items]
Cash Proceeds from Legal Settlements	$ 103
Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Payments for Foreign Currency Derivative Instruments Not Designated as Hedging Instruments			$ 180