Share capital - Rio Tinto Limited - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of classes of share capital [line items]
Number of shares held (in shares)	0	0	0
Rio Tinto Limited
Disclosure of classes of share capital [line items]
Value of shares purchased by employee share ownership trusts	$ 76	$ 63	$ 114
Number of shares held (in shares)	828,338

The number of shares in the entity held by the entity or by its subsidiaries or associates. [Refer: Associates [member]; Subsidiaries [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 79
-Subparagraph a
-Clause vi
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_79_a_vi&doctype=Standard
-URIDate 2020-01-01

Name:	ifrs-full_SharesInEntityHeldByEntityOrByItsSubsidiariesOrAssociates
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant