XML 458 R255.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Post-retirement benefits - Summary of funding policy and contributions to plans (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure of net defined benefit liability (asset) [Line Items] |  |  |
Contributions to defined benefit plans | $ 248 | $ 404 | $ 464
Contributions to defined contribution plans | 244 | 243 | 240
Contributions to industry-wide plans |  | 12 | 17
Total | 492 | $ 659 | $ 721
Pension benefits [member] |  |  |
Disclosure of net defined benefit liability (asset) [Line Items] |  |  |
Contributions to defined benefit plans | 204 |  |
Contributions to defined contribution plans | 242 |  |
Total | 446 |  |
Other Benefits [member] |  |  |
Disclosure of net defined benefit liability (asset) [Line Items] |  |  |
Contributions to defined benefit plans | 44 |  |
Contributions to defined contribution plans | 2 |  |
Total | $ 46 |  |

X
- Definition The decrease (increase) in net defined benefit liability (asset) resulting from contributions to a defined benefit plan by the employer. [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 2017-01-01 -Paragraph 141 -Subparagraph f -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_141_f&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_ContributionsToPlanByEmployerNetDefinedBenefitLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfNetDefinedBenefitLiabilityAssetLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of employer contributions to retirement benefit plans. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 26 -IssueDate 2017-01-01 -Paragraph 35 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=26&date=2017-03-01&anchor=para_35_b_i&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_EmployerContributions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Contributions to Defined Contribution Plans + References No definition available. + Details
Name: | rio_ContributionsToDefinedContributionPlans
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The decrease (increase) in the net defined benefit liability (asset) resulting from employer contributions to industry wide plans. + References No definition available. + Details
Name: | rio_ContributionsToIndustryWidePlans
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | ifrs-full_DefinedBenefitPlansAxis=rio_DefinedBenefitPensionPlansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_DefinedBenefitPlansAxis=rio_OtherDefinedBenefitPlansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |