Debt Instrument, Floor Interest Rate

No definition available.

Name:	btu_DebtInstrumentFloorInterestRate
Namespace Prefix:	btu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Total fresh-start adjustment to long-term debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6918054&loc=SL2890621-112765

+ Details

Name:	us-gaap_FreshStartAdjustmentIncreaseDecreaseLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FreshStartAdjustmentsTypeOfFreshStartAdjustmentAxis=btu_EffectofReorganizationPlanMember
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Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=btu_A6.375SeniorSecuredNotesDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=btu_SuccessorCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=btu_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
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Debt Securities (Details) - USD ($)	12 Months Ended
Debt Securities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Apr. 11, 2018	Apr. 03, 2017	Apr. 01, 2017	Feb. 15, 2017
Fresh-Start Adjustment [Line Items]
Fresh-Start Adjustment, Increase (Decrease), Long-term Debt					$ 950,000,000.0
6.000% Senior Secured Notes due March 2022 \| Senior Notes
Fresh-Start Adjustment [Line Items]
Stated interest rate	6.00%
6.000% Senior Secured Notes due March 2022 \| Senior Notes \| Effect of Plan
Fresh-Start Adjustment [Line Items]
Principal amount						$ 500,000,000.0
6.375% Senior Secured Notes due March 2025 \| Senior Notes
Fresh-Start Adjustment [Line Items]
Stated interest rate	6.375%
6.375% Senior Secured Notes due March 2025 \| Senior Notes \| Effect of Plan
Fresh-Start Adjustment [Line Items]
Principal amount						$ 500,000,000.0
Successor Credit Agreement \| Senior Secured Term Loan due 2025, net of original issue discount
Fresh-Start Adjustment [Line Items]
Principal amount	$ 400,000,000.0
Basis spread on variable rate	2.75%
Floor interest rate			1.00%
Successor Credit Agreement \| Senior Secured Term Loan due 2025, net of original issue discount \| Effect of Plan
Fresh-Start Adjustment [Line Items]
Principal amount				$ 950,000,000.0
London Interbank Offered Rate (LIBOR) \| Successor Credit Agreement \| Senior Secured Term Loan due 2025, net of original issue discount
Fresh-Start Adjustment [Line Items]
Basis spread on variable rate		2.75%