XML 237 R70.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Derivatives and Fair Value Measurements - Textual (Details) $ in Millions | 3 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Sep. 30, 2024 AUD ($) | Jun. 30, 2024 $ / $ | Dec. 31, 2023 AUD ($)
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Collateral, Right to Reclaim Cash | $ 0.0 | $ 255.5 |  | $ 0.0 | $ 255.5 |  |  |  |
Revenue from physical sale of coal |  |  |  | $ 4,946.7 | 4,981.9 | $ 3,318.3 |  |  |
Unobservable Measurement Input, Uncertainty, Description |  |  |  | 10 |  |  |  |  |
Fair Value, Inputs, Level 1, 2 and 3 |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Net financial asset (liability) | 0.0 |  |  | $ 0.0 |  |  |  |  |
Total net assets (liabilities) |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Net financial asset (liability) | 6.6 | (192.5) |  | 6.6 | (192.5) |  |  |  |
Coal Trading |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Collateral, Right to Reclaim Cash |  | 57.5 |  |  | 57.5 |  |  |  |
Purchases |  |  |  | 0.0 | 0.2 | 0.0 |  |  |
Designated as Hedging Instrument |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Total Unrealized gain (loss) recognized in income on derivatives |  |  |  | 154.9 | (28.5) | (121.1) |  |  |
Designated as Hedging Instrument | Net Amount |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative Liability, Collateral, Right to Reclaim Cash, Offset |  | 198.0 |  |  | 198.0 |  |  |  |
Foreign currency option contracts |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Notional Amount |  |  |  |  |  |  |  |  | $ 456,000,000
Foreign currency option contracts | Subsequent Event |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Notional Amount |  |  |  |  |  |  | $ 483,000,000 |  |
Foreign currency option contracts | Total net assets (liabilities) |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Net financial asset (liability) | 6.2 | 3.0 |  | 6.2 | 3.0 |  |  |  |
Foreign currency option contracts | Designated as Hedging Instrument |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Total Unrealized gain (loss) recognized in income on derivatives |  |  |  | 7.4 | (2.3) | (7.5) |  |  |
Diesel Fuel Hedge Contracts |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Notional Amount |  |  |  |  |  |  |  |  | 0
Financial trading contracts | Total net assets (liabilities) |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Net financial asset (liability) | 0.0 | 11.7 |  | 0.0 | 11.7 |  |  |  |
Financial trading contracts | Designated as Hedging Instrument |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Total Unrealized gain (loss) recognized in income on derivatives |  |  |  | (11.5) | 9.6 | 1.5 |  |  |
Gain (Loss) on Derivative Instruments | Designated as Hedging Instrument |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Total Unrealized gain (loss) recognized in income on derivatives |  | (65.0) | $ (86.0) |  |  |  |  |  |
Forward Contracts | Designated as Hedging Instrument |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Total Unrealized gain (loss) recognized in income on derivatives | 0.0 | (29.0) |  |  |  | (29.0) |  |  |
Coal derivative contracts related to forecasted sales |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Notional Amount |  |  |  |  |  |  |  |  | $ 0
Derivative contracts related to forecasted sales | Total net assets (liabilities) |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Net financial asset (liability) | $ 0.0 | $ (209.7) |  | 0.0 | (209.7) |  |  |  |
Derivative contracts related to forecasted sales | Designated as Hedging Instrument |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Total Unrealized gain (loss) recognized in income on derivatives |  |  |  | $ 159.0 | $ (35.8) | $ (115.1) |  |  |
Scenario, Forecast | Foreign currency option contracts |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Floor Price |  |  |  |  |  |  | 0.59 |  |
Derivative, Cap Price |  |  |  |  |  |  | 0.72 |  |
Scenario, Forecast | Foreign currency option contracts | Minimum |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Exchange Rate Cap | $ / $ |  |  |  |  |  |  |  | 0.69 |
Scenario, Forecast | Foreign currency option contracts | Maximum |  |  |  |  |  |  |  |  |
Derivatives, Fair Value [Line Items] |  |  |  |  |  |  |  |  |
Derivative, Exchange Rate Cap | $ / $ |  |  |  |  |  |  |  | 0.72 |

X
- Definition Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 5 -SubTopic 10 -Topic 815 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480463/815-10-45-5 + Details
Name: | us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract. + References No definition available. + Details
Name: | us-gaap_DerivativeCapPrice
Namespace Prefix: | us-gaap_
Data Type: | srt-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 55 -Paragraph 13 -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-13 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 20 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-20 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (d)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-8 + Details
Name: | us-gaap_DerivativeCollateralRightToReclaimCash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Cap rate on a foreign currency derivative for example, but not limited to, a cap or a collar. + References No definition available. + Details
Name: | us-gaap_DerivativeExchangeRateCap1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Floor rate on a price risk derivative such as a floor or a collar. A payment or receipt is triggered if the market rate falls below the floor rate on the contract. + References No definition available. + Details
Name: | us-gaap_DerivativeFloorPrice
Namespace Prefix: | us-gaap_
Data Type: | srt-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of right to receive cash collateral under master netting arrangements offset against derivative liabilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 5 -SubTopic 10 -Topic 815 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480463/815-10-45-5 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -SubTopic 20 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 + Details
Name: | us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Description of uncertainty of fair value measurement from use of unobservable input, including, but not limited to, inter-relationships among inputs used in fair value measurement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (g) -SubTopic 10 -Topic 820 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_FairValueMeasurementsSensitivityAnalysisDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-11 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 15 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-15 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (c) -SubTopic 10 -Topic 815 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4C + Details
Name: | us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(g)(1)(ii)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 323 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481687/323-10-50-3 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 28 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482907/825-10-50-28 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(1)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1A -Subparagraph (SX 210.13-01(a)(4)(i)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1A -Subparagraph (SX 210.13-01(a)(4)(ii)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1A -Subparagraph (SX 210.13-01(a)(4)(iii)(A)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1A -Subparagraph (SX 210.13-01(a)(4)(iv)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1A -Subparagraph (SX 210.13-01(a)(5)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1B -Subparagraph (SX 210.13-02(a)(4)(i)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1B -Subparagraph (SX 210.13-02(a)(4)(iii)(A)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1B -Subparagraph (SX 210.13-02(a)(4)(iii)(B)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1B -Subparagraph (SX 210.13-02(a)(4)(iv)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1B -Subparagraph (SX 210.13-02(a)(5)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 30 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-30 Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-42 Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-22 Reference 18: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-32 Reference 19: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 40 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-40 Reference 20: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-22 Reference 21: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-32 Reference 22: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 41 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-41 Reference 23: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-05(b)(2)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479557/942-235-S99-1 + Details
Name: | us-gaap_Revenues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel12And3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TradingActivityByTypeAxis=btu_CoalTradingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | btu_AmountClassificationAxis=btu_NetAmountMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=btu_DieselFuelHedgeContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CoalContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_GainLossOnDerivativeInstrumentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForwardContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=btu_CoalDerivativeContractsRelatedToForecastedSalesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=btu_PhysicalCommodityPurchaseSaleContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |