Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

+ Details

Name:	us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

+ Details

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

+ Details

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Describe the approximate term of the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

+ Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=cop_AustraliaPacificAplngMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=cop_FinanceReserveGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=cop_GuaranteeNaturalGasDeliveryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=cop_MaxPotentialFuturePaymentsRecklessBreachMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=cop_MaxPotentialFuturePaymentsProrataShareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=cop_AplngContinuedDevelopmentMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=cop_OtherGuaranteesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_IndemnificationGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Guarantees - Textual (Details) - USD ($) $ in Millions	6 Months Ended
Guarantees - Textual (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Guarantor Obligations [Line Items]
Environmental accruals for known contamination in carrying amount recorded for indemnifications	$ 188	$ 180
Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Ownership percentage in equity investment	37.50%
Finance Reserve Guarantee [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Terms of Guarantees Outstanding	10 years
Maximum potential amount of future payments	$ 170
Guarantor Obligations, Current Carrying Value	$ 14
Guarantee existing sales agreement of natural gas delivery \| Australia Pacific APLNG [Member] \| Maximum [Member]
Guarantor Obligations [Line Items]
Terms of Guarantees Outstanding	1 to 21 years
Max potential future payments-reckless breach [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	$ 1,300
Max potential future payments-prorata share [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	710
Continued development [Member] \| Australia Pacific APLNG [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	180
Guarantor Obligations, Current Carrying Value	$ 11
Continued development [Member] \| Australia Pacific APLNG [Member] \| Maximum [Member]
Guarantor Obligations [Line Items]
Terms of Guarantees Outstanding	16 to 24 years or the life of the venture
Other Guarantees [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments	$ 740
Guarantor Obligations, Current Carrying Value	$ 11
Other Guarantees [Member] \| Maximum [Member]
Guarantor Obligations [Line Items]
Terms of Guarantees Outstanding	two to five years
Indemnifications [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 50