v2.4.0.6

Employee Benefit Plans (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
U.S. (Pension Benefits) [Member]
Employee Benefit Plans (Textual) [Abstract]
Company contributions	$ 52
Int'l (Pension Benefits) [Member]
Employee Benefit Plans (Textual) [Abstract]
Company contributions	$ 50

X

- Details

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

X

- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

+ Details

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