Significant accounting policies, judgements, estimates and assumptions - Significant judgement: accounting for interests in other entities (Details) - Rosneft - shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Disclosure of associates [line items]
Voting shares held in associate	19.75%
Proportion of Economic Interest in Associate	22.03%	19.75%
JSC Rosneftegaz
Disclosure of associates [line items]
Voting shares held in associate	40.40%	50.00%
Number of shares owned in addition to proportion of voting shares owned (in shares)		1

The proportion of the voting rights in an associate held by the entity. [Refer: Associates [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2020-01-01
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-Subparagraph b
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-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2020-01-01
-Paragraph 16
-Subparagraph b
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration