XML 391 R188.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Financial instruments and risk management - Capital and liquidity risk management - Additional information (Detail) - USD ($) $ in Millions | 4 Months Ended | 12 Months Ended
--- | --- | ---
Apr. 30, 2018 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Net debt |  | $ (255) | $ 3,845 | $ 9,587
Net cash |  | 11,821 | 13,884 | 8,465
Buy-back of bonds | $ 1,900 |  | 2,500 | $ 7,500
Borrowings |  | $ 12,752 | 15,176 |
Percentage of change in spot price |  | 15.00% |  |
Level 1 [member] |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Borrowings |  | $ 7,500 | 9,600 |
Borrowings at fair value |  | 8,300 | 10,900 |
Level 3 [member] |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Borrowings |  | 4,200 | 4,100 |
Borrowings at fair value |  | $ 4,600 | 4,700 |
Percentage of increase in copper price |  | 10.00% |  |
Period of London metal exchange curve |  | ten-year |  |
Decrease in carrying value of forward contract due to long-term metal pricing assumptions |  | $ 22 | 41 |
Increase in carrying value of forward contract due to long-term metal pricing assumptions |  | $ 14 | 22 |
Percentage of change in coal spot price |  | 15.00% |  |
Increase in carrying value of forward contract due to coal spot price assumptions |  | $ 181 |  |
Decrease in carrying value of forward contract due to decrease in spot price |  | 95 |  |
Capital and liquidity risk management [member] |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Net debt |  | (255) | $ 3,845 |
Net cash |  | $ 300 |  |
Net debt to total capital percentage |  | (1.00%) | 7.00% |
Description of interest coverage on debt |  | 22 times | 14 times |
Revolving credit facilities period |  | 1 year |  |
Borrowing maturity |  | November 2022 |  |
Description of rating agencies used |  | Standard & Poor’s and Moody’s investor services |  |
Capital and liquidity risk management [member] | Rio Tinto Finance (USA) plc and Rio Tinto Finance (USA) Limited [member] |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Buy-back of bonds |  | $ 1,900 | $ 2,500 |
Aggregate cash outflow before fees |  | 2,000 | $ 2,700 |
Capital and liquidity risk management [member] | November Two Thousand And Twenty One |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Revolving credit facilities |  | 1,900 |  |
Capital and liquidity risk management [member] | November Two Thousand And Twenty Two |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Revolving credit facilities |  | $ 5,600 |  |
Bottom of range [Member] | Capital and liquidity risk management [member] |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Percentage of underlying earnings |  | 40.00% |  |
Top of range [Member] | Capital and liquidity risk management [member] |  |  |  |
Disclosure Of Financial Instruments [Line Items] |  |  |  |
Percentage of underlying earnings |  | 60.00% |  |

X
- Definition The amount of outstanding funds that the entity is obligated to repay. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_55&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_Borrowings
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The maturity of borrowings. [Refer: Borrowings] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 7 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_7&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_BorrowingsMaturity
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash flows from (used in) operating activities, which are the principal revenue-producing activities of the entity and other activities that are not investing or financing activities. [Refer: Revenue] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 10 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_10&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 50 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_50_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_CashFlowsFromUsedInOperatingActivities
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition The description of credit rating agencies used to evaluate the credit quality of the entity's financial assets. [Refer: Financial assets] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Note Expiry date 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph IG24 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_IG24_b&doctype=Implementation%20Guidance&book=B -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Note Expiry date 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 36 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_36_c&doctype=Standard&book=B -URIDate 2017-03-09 + Details
Name: | ifrs-full_DescriptionOfRatingAgenciesUsed
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
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_DisclosureOfFinancialInstrumentsLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of net debt of the entity. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_NetDebt
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash outflow for repayments of bonds, notes and debentures. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 17 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_17&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_RepaymentsOfBondsNotesAndDebentures
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Borrowings at fair value. + References No definition available. + Details
Name: | rio_BorrowingsAtFairValue
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Decrease in carrying value of forward contract due to decrease in spot price. + References No definition available. + Details
Name: | rio_DecreaseInCarryingValueOfForwardContractDueToDecreaseInSpotPrice
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Decrease in carrying value of forward contract due to long-term metal pricing assumptions. + References No definition available. + Details
Name: | rio_DecreaseInCarryingValueOfForwardContractDueToLongTermMetalPricingAssumptions
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of interest cover times. + References No definition available. + Details
Name: | rio_DescriptionOfInterestCoverTimes
Namespace Prefix: | rio_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Increase in carrying value of forward contract due to coal spot price assumptions. + References No definition available. + Details
Name: | rio_IncreaseInCarryingValueOfForwardContractDueToCoalSpotPriceAssumptions
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Increase in carrying value of forward contract due to long-term metal pricing assumptions. + References No definition available. + Details
Name: | rio_IncreaseInCarryingValueOfForwardContractDueToLongTermMetalPricingAssumptions
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Net debt to capital percentage. + References No definition available. + Details
Name: | rio_NetDebtToCapitalPercentage
Namespace Prefix: | rio_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of change in coal spot price. + References No definition available. + Details
Name: | rio_PercentageOfChangeInCoalSpotPrice
Namespace Prefix: | rio_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of change in coal price. + References No definition available. + Details
Name: | rio_PercentageOfChangeInSpotPrice
Namespace Prefix: | rio_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of increase in copper price. + References No definition available. + Details
Name: | rio_PercentageOfIncreaseInCopperPrice
Namespace Prefix: | rio_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of underlying earnings related to dividend policy. + References No definition available. + Details
Name: | rio_PercentageOfUnderlyingEarningsRelatedToDividendPolicy
Namespace Prefix: | rio_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period of London metal exchange curve. + References No definition available. + Details
Name: | rio_PeriodOfLondonMetalExchangeCurve
Namespace Prefix: | rio_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Redemption of bonds. + References No definition available. + Details
Name: | rio_RedemptionOfBonds
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Revolving credit facilities. + References No definition available. + Details
Name: | rio_RevolvingCreditFacilities
Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Revolving credit facilities extension options term. + References No definition available. + Details
Name: | rio_RevolvingCreditFacilitiesExtensionOptionsTerm
Namespace Prefix: | rio_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_LevelsOfFairValueHierarchyAxis=ifrs-full_Level1OfFairValueHierarchyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_LevelsOfFairValueHierarchyAxis=ifrs-full_Level3OfFairValueHierarchyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfRisksAxis=rio_CapitalAndLiquidityRiskManagementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=rio_RioTintoFinanceUsaPlcAndRioTintoFinanceUsaLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_MaturityAxis=rio_NovemberTwoThousandAndTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_MaturityAxis=rio_NovemberTwoThousandAndTwentyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |