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Portion of the 2019 Revolver commitments which matures in 2023

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Debt Instrument, Covenant, Leverage Ratio

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Revolving Credit Facility, Fee on Unused Borrowings

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

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Long-term Debt - Textuals (Details) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended	30 Months Ended
Long-term Debt - Textuals (Details) - USD ($)	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Sep. 30, 2019	Sep. 30, 2023	Nov. 30, 2020	Oct. 01, 2018	Aug. 09, 2018	Sep. 18, 2017	Apr. 03, 2017	Feb. 15, 2017
Debt Instrument [Line Items]
Debt issuance cost	$ 59,800,000			$ 59,800,000		$ 68,900,000	$ 59,800,000
Interest expense	$ 35,400,000	$ 38,200,000		107,200,000	$ 112,800,000
Repayment of Long-term Debt, Long-term Lease Obligation, and Capital Security				$ 23,900,000	73,000,000.0
Successor Credit Agreement
Debt Instrument [Line Items]
Debt Instrument, Covenant, Fixed Charge Coverage Ratio	2.25
Senior Notes \| 6.000% Senior Secured Notes due March 2022
Debt Instrument [Line Items]
Stated interest rate	6.00%			6.00%		6.00%	6.00%
Debt Instrument, Restricted Payments, Amount Paid											$ 10.00
Debt Instrument, Restricted Payments, Principal Amount Used to Calculate Payments											1,000
Long-term debt	$ 500,000,000.0			$ 500,000,000.0		$ 500,000,000.0	$ 500,000,000.0
Senior Notes \| 6.000% Senior Secured Notes due March 2022 \| Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	103.00%
Senior Notes \| 6.000% Senior Secured Notes due March 2022 \| Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption price, percentage	101.50%
Senior Notes \| 6.000% Senior Secured Notes due March 2022 \| Effect of Plan
Debt Instrument [Line Items]
Principal amount														$ 500,000,000.0
Stated interest rate														6.00%
Senior Notes \| 6.375% Senior Secured Notes due March 2025
Debt Instrument [Line Items]
Stated interest rate	6.375%			6.375%		6.375%	6.375%
Debt Instrument, Restricted Payments, Amount Paid											30.00
Debt Instrument, Restricted Payments, Principal Amount Used to Calculate Payments											1,000
Long-term debt	$ 500,000,000.0			$ 500,000,000.0		$ 500,000,000.0	$ 500,000,000.0
Senior Notes \| 6.375% Senior Secured Notes due March 2025 \| Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	104.80%
Senior Notes \| 6.375% Senior Secured Notes due March 2025 \| Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Redemption price, percentage	103.20%
Senior Notes \| 6.375% Senior Secured Notes due March 2025 \| Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Redemption price, percentage	101.60%
Senior Notes \| 6.375% Senior Secured Notes due March 2025 \| Effect of Plan
Debt Instrument [Line Items]
Principal amount														$ 500,000,000.0
Stated interest rate														6.375%
Senior Notes \| 6.00% And 6.375% Senior Secured Notes, Successor Notes
Debt Instrument [Line Items]
Debt issuance cost	$ 49,500,000			49,500,000			$ 49,500,000
Interest expense	$ 18,100,000	19,100,000		$ 54,200,000	54,000,000.0
Senior Notes \| 6.00% And 6.375% Senior Secured Notes, Successor Notes \| Domestic
Debt Instrument [Line Items]
Collateral, capital stock, percent	100.00%			100.00%			100.00%
Senior Notes \| 6.00% And 6.375% Senior Secured Notes, Successor Notes \| Export
Debt Instrument [Line Items]
Collateral, non-voting capital stock, percent	100.00%			100.00%			100.00%
Collateral, voting capital stock, percent	65.00%			65.00%			65.00%
Senior Notes \| 6.00% And 6.375% Senior Secured Notes, Successor Notes \| Peabody Investments (Gibraltar) Limited
Debt Instrument [Line Items]
Collateral, non-voting capital stock, percent	100.00%			100.00%			100.00%
Collateral, voting capital stock, percent	65.00%			65.00%			65.00%
Senior Notes \| Successor Credit Agreement
Debt Instrument [Line Items]
Debt Instrument, Restricted Payments Basket											650,000,000.0
Debt Instrument, Restricted Payments Basket, Annual Limit											150,000,000.0
Aggregate consent payments											$ 19,800,000
Other Expenses						1,500,000
Term Loan \| Successor Credit Agreement
Debt Instrument [Line Items]
Principal amount	$ 400,000,000.0			$ 400,000,000.0			$ 400,000,000.0
Interest expense	5,600,000	5,100,000		17,000,000.0	18,500,000
Debt Instrument, Restricted Payments Basket												$ 450,000,000.0
Original issue discount and deferred finance costs	$ 37,300,000			$ 37,300,000			$ 37,300,000
Debt Instrument, Principal Prepayment, Percent of Principal Amount if Repaid Before October 2018										101.00%
Mandatory principal prepayment, percent of excess cash flow	75.00%			75.00%			75.00%
Mandatory principal prepayment, if required, period payable, threshold	100 days
Excess proceeds from sales of assets, threshold ($10 million or greater)	$ 10,000,000.0			$ 10,000,000.0			$ 10,000,000.0
Repayments of Debt			$ 46,000,000.0				556,000,000.0
Payment for Debt Extinguishment or Debt Prepayment Cost							546,000,000.0
Restricted payments threshold	$ 450,000,000.0			$ 450,000,000.0			$ 450,000,000.0					50,000,000.0
Debt Instrument, Covenant, Fixed Charge Coverage Ratio	2.00
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00
Debt Instrument [Line Items]
Mandatory principal prepayment, percent of excess cash flow	50.00%			50.00%			50.00%
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00 \| Maximum
Debt Instrument [Line Items]
Total Leverage Ratio	2.00			2.00			2.00
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal to 2.00 to 1.00 Greater Than 1.50 to 1.00 \| Minimum
Debt Instrument [Line Items]
Total Leverage Ratio	1.50			1.50			1.50
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00
Debt Instrument [Line Items]
Mandatory principal prepayment, percent of excess cash flow	25.00%			25.00%			25.00%
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00 \| Maximum
Debt Instrument [Line Items]
Total Leverage Ratio	1.50			1.50			1.50
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal to 1.50 to 1.00 Greater Than 1.00 to 1.00 \| Minimum
Debt Instrument [Line Items]
Total Leverage Ratio	1.00			1.00			1.00
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal to 1.00 to 1.00
Debt Instrument [Line Items]
Mandatory principal prepayment, percent of excess cash flow	0.00%			0.00%			0.00%
Total Leverage Ratio	1.00			1.00			1.00
Term Loan \| Successor Credit Agreement \| Total Leverage Ration Less Or Equal 2.00 to 1.00
Debt Instrument [Line Items]
Total Leverage Ratio	2.00			2.00			2.00
Term Loan \| Successor Credit Agreement \| Total Leverage Ratio Less or Equal 1.25 to 1.00
Debt Instrument [Line Items]
Total Leverage Ratio	1.25			1.25			1.25
Dividend payment and stock purchase payment threshold	$ 25,000,000.0			$ 25,000,000.0			$ 25,000,000.0
Term Loan \| Successor Credit Agreement \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%
Term Loan \| Successor Credit Agreement \| Effect of Plan
Debt Instrument [Line Items]
Principal amount													$ 950,000,000.0
Term Loan \| Senior Secured Term Loan due 2025, net of original issue discount
Debt Instrument [Line Items]
Secured Debt													$ 950,000,000.0
Long-term debt	$ 393,000,000.0			393,000,000.0		$ 395,900,000	393,000,000.0
Line of Credit \| 2017 Revolver \| Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt												350,000,000.0
Revolving Credit Facility \| 2017 Revolver
Debt Instrument [Line Items]
Debt issuance cost	5,700,000			5,700,000			5,700,000					4,700,000
Interest expense	1,400,000	$ 1,300,000		4,500,000	$ 4,300,000
Line of Credit Facility, Maximum Borrowing Capacity	565,000,000.0			565,000,000.0			565,000,000.0					$ 350,000,000.0
2019 Revolver commitments, matures 2023	540,000,000.0			$ 540,000,000.0			$ 540,000,000.0
Unrestricted Cash Netting Limit	$ 800,000,000.0
Debt Instrument, Base Interest Rate	3.375%			3.375%			3.375%
Revolving Credit Facility, Fee on Unused Borrowings	0.50%			0.50%			0.50%
Aggregate Letters of Credit, Maximum	$ 66,400,000			$ 66,400,000			$ 66,400,000
Revolving Credit Facility \| 2017 Revolver \| Total Leverage Ration Less Or Equal 2.00 to 1.00
Debt Instrument [Line Items]
Total Leverage Ratio	2.00			2.00			2.00
Revolving Credit Facility \| 2017 Revolver \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	3.25%
Scenario, Forecast \| Revolving Credit Facility \| 2017 Revolver
Debt Instrument [Line Items]
2019 Revolver commitments, matures 2023								$ 540,000,000.0
2019 Revolver commitments, matures 2020									$ 25,000,000.0