Post-retirement benefits - Summary of movement in present value of obligation (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Changes in net defined benefit liability (asset) [abstract]
Beginning balance	$ 1,028	$ 2,273
Changes in financial assumptions gains	(3,410)	(655)	$ 1,242
Currency exchange rate (losses)/gains	(35)	(2)
Ending balance	470	1,028	2,273
Pension benefits
Changes in net defined benefit liability (asset) [abstract]
Beginning balance	194
Currency exchange rate (losses)/gains	(57)
Ending balance	(152)	194
Other benefits
Changes in net defined benefit liability (asset) [abstract]
Beginning balance	834
Currency exchange rate (losses)/gains	22
Ending balance	622	834
Present value of defined benefit obligation
Changes in net defined benefit liability (asset) [abstract]
Beginning balance	15,728	17,178
Current employer service costs	(143)	(167)
Past service cost	0	(2)
Settlements	0	380
Interest on obligation	370	328
Contributions by plan participants	20	22
Benefits paid	783	837
Experience (losses)/gains	(170)	89
Changes in financial assumptions gains	3,563	521
Changes in demographic assumptions gains	17	45
Currency exchange rate (losses)/gains	891	97
Ending balance	11,177	15,728	$ 17,178
Present value of defined benefit obligation \| Pension benefits
Changes in net defined benefit liability (asset) [abstract]
Beginning balance	14,894
Current employer service costs	(136)
Past service cost	0
Settlements	0
Interest on obligation	346
Contributions by plan participants	20
Benefits paid	743
Experience (losses)/gains	(177)
Changes in financial assumptions gains	3,390
Changes in demographic assumptions gains	16
Currency exchange rate (losses)/gains	869
Ending balance	10,555	14,894
Present value of defined benefit obligation \| Other benefits
Changes in net defined benefit liability (asset) [abstract]
Beginning balance	834
Current employer service costs	(7)
Past service cost	0
Settlements	0
Interest on obligation	24
Contributions by plan participants	0
Benefits paid	40
Experience (losses)/gains	7
Changes in financial assumptions gains	173
Changes in demographic assumptions gains	1
Currency exchange rate (losses)/gains	22
Ending balance	$ 622	$ 834

The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in demographic assumptions that result in remeasurements of the net defined benefit liability (asset). Demographic assumptions deal with matters such as: (a) mortality; (b) rates of employee turnover, disability and early retirement; (c) the proportion of plan members with dependants who will be eligible for benefits; (d) the proportion of plan members who will select each form of payment option available under the plan terms; and (e) claim rates under medical plans. [Refer: Net defined benefit liability (asset)]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph c
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_c_ii&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ActuarialGainsLossesArisingFromChangesInDemographicAssumptionsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in financial assumptions that result in remeasurements of the net defined benefit liability (asset). Financial assumptions deal with items such as: (a) the discount rate; (b) benefit levels, excluding any cost of the benefits to be met by employees, and future salary; (c) in the case of medical benefits, future medical costs, including claim handling costs (ie the costs that will be incurred in processing and resolving claims, including legal and adjuster's fees); and (d) taxes payable by the plan on contributions relating to service before the reporting date or on benefits resulting from that service. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph c
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_c_iii&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from experience adjustments that result in remeasurements of the net defined benefit liability (asset). Experience adjustments deal with the effects of differences between the previous actuarial assumptions and what has actually occurred. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_c&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ActuarialGainsLossesArisingFromExperienceAdjustmentsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	ifrs-full_ChangesInNetDefinedBenefitLiabilityAssetAbstract
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from contributions to a defined benefit plan by plan participants. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_f&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ContributionsToPlanByPlanParticipantsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_a&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_CurrentServiceCostNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from settlements. Settlements are transactions that eliminate all further legal or constructive obligations for part or all of the benefits provided under a defined benefit plan, other than a payment of benefits to, or on behalf of, employees that is set out in the terms of the plan and included in the actuarial assumptions. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]; Actuarial assumptions [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_d&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_GainsLossesArisingFromSettlementsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from changes in foreign exchange rates. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_e&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_IncreaseDecreaseThroughChangesInForeignExchangeRatesNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from the passage of time. [Refer: Interest expense; Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_b&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 140
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_140_a&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_LiabilityAssetOfDefinedBenefitPlans
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from past service cost. Past service cost is the change in the present value of the defined benefit obligation for employee service in prior periods, resulting from a plan amendment (the introduction or withdrawal of, or changes to, a defined benefit plan) or a curtailment (a significant reduction by the entity in the number of employees covered by a plan). [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

+ Details

Name:	ifrs-full_PastServiceCostNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_g&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_PaymentsFromPlanNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ifrs-full_CharacteristicsOfDefinedBenefitPlansAxis=ifrs-full_PensionDefinedBenefitPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CharacteristicsOfDefinedBenefitPlansAxis=rio_OtherDefinedBenefitPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_NetDefinedBenefitLiabilityAssetAxis=ifrs-full_PresentValueOfDefinedBenefitObligationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: