Equity method investment and joint ventures.

No definition available.

Name:	cop_EquityMethodInvestmentAndJointVenturesAbstract
Namespace Prefix:	cop_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of credit facility outstanding as distinguished from maximum borrowing capacity.

+ References

No definition available.

+ Details

Name:	cop_LineOfCreditFacilityValueOutstanding
Namespace Prefix:	cop_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of a long-term obligation that has been refinanced during the period.

+ References

No definition available.

+ Details

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

- Definition

For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.3)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_DueFromRelatedParties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow for the extinguishment of long-term borrowing, with the highest claim on the assets of the entity in case of bankruptcy or liquidation, before its maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

Name:	us-gaap_EarlyRepaymentOfSeniorDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8813-108599

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the frequency of periodic payments, which may be presented in a variety of ways (for example, monthly, quarterly, annually).

+ References

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Details

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

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cop_DomesticLenderMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cop_ForeignLender1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cop_ForeignLender2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cop_USPrivatePlacementBondMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cop_CommericalBanksMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Investments, Loans and Long-Term Receivables - Textual (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2012
Equity method investments
Loan balance with affiliated company			$ 219	$ 339
APLNG [Member]
Equity method investments
Project finance facility, maximum borrowing capacity					$ 8,500
Line Of Credit Facility Value Outstanding			6,200
Book value of equity method investment			$ 6,877
Long Term Debt Refinanced Amount		$ 3,200
Line of Credit Facility, Expiration Date			Mar. 31, 2029
Line of Credit Facility, Frequency of Payments			bi-annual
APLNG [Member] \| Export-Import Bank of the US [Member]
Equity method investments
Project finance facility, maximum borrowing capacity					2,900
APLNG [Member] \| Export-Import Bank of China [Member]
Equity method investments
Project finance facility, maximum borrowing capacity					2,700
Early Repayment of Senior Debt	$ 1,400	1,000
Line of Credit Facility, Expiration Date			Sep. 30, 2030
Line of Credit Facility, Frequency of Payments			bi-annual
APLNG [Member] \| Australian and International Commercial Bank Syndicate [Member]
Equity method investments
Project finance facility, maximum borrowing capacity					$ 2,900
Early Repayment of Senior Debt		2,200
APLNG [Member] \| U S Private Placement Bond [Member]
Equity method investments
Project finance facility, maximum borrowing capacity	$ 1,400	600
Line of Credit Facility, Expiration Date			Sep. 30, 2030
Line of Credit Facility, Frequency of Payments			bi-annual
APLNG [Member] \| Commerical Banks [Member]
Equity method investments
Project finance facility, maximum borrowing capacity		$ 2,600
Line of Credit Facility, Expiration Date			Mar. 31, 2028
Line of Credit Facility, Frequency of Payments			bi-annual
QG3 [Member]
Equity method investments
Loan balance with affiliated company			$ 219