Long-term Debt - Textual (Details) - USD ($)		1 Months Ended	12 Months Ended			54 Months Ended
	Jan. 29, 2021	Apr. 30, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Jan. 14, 2022	Jun. 04, 2021	Apr. 03, 2017	Feb. 15, 2017
Debt Instrument [Line Items]
Debt issuance cost			$ 34,800,000	$ 42,700,000
Interest expense			183,400,000	139,800,000	$ 144,000,000.0
Net (gain) loss on early debt extinguishment			33,200,000	$ 0	(200,000)
Professional Fees			$ 10,600,000
Common Stock, shares authorized (in shares)			450,000,000.0	450,000,000.0
Common Stock, shares issued (in shares)			176,300,000	140,500,000
Payment for debt exchange	$ 9,400,000
Payment for debt exchange early tender premiums	4,000,000
Proceeds from common stock issuances, net of costs			$ 269,800,000	$ 0	$ 0
At Market Issuance
Debt Instrument [Line Items]
Common Stock, shares authorized (in shares)			32,500,000					12,500,000
Sale of Stock, Number of Shares Issued in Transaction			24,800,000
Common Stock, shares issued (in shares)			24,800,000	0	0
At Market Issuance | Common Stock
Debt Instrument [Line Items]
Proceeds from common stock issuances, net of costs			$ 269,800,000
Open Market Purchase
Debt Instrument [Line Items]
Payment for debt extinguishment or debt prepayment cost			232,400,000
Net (gain) loss on early debt extinguishment			(28,800,000)
Write off of deferred debt issuance cost			9,700,000
Debt for Equity Exchange
Debt Instrument [Line Items]
Net (gain) loss on early debt extinguishment			$ 900,000
Common Stock, shares issued (in shares)			10,000,000	0	0
Accounts Receivable Securitization Program, April 3, 2020
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity			$ 26,300,000
Exit facility, maximum borrowing capacity									$ 250,000,000
Senior Notes | 6.000% Senior Secured Notes due March 2022 (2022 Notes)
Debt Instrument [Line Items]
Long-term debt			$ 23,100,000	$ 459,000,000.0
Stated interest rate			6.00%
Aggregate principal amount of debt exchanged	398,700,000
Senior Notes | 6.000% Senior Secured Notes due March 2022 (2022 Notes) | Debt for Equity Exchange
Debt Instrument [Line Items]
Proceeds from common stock issuances, net of costs			$ 37,300,000
Senior Notes | 6.375% Senior Secured Notes due March 2025 (2025 Notes)
Debt Instrument [Line Items]
Long-term debt			$ 334,900,000	500,000,000.0
Stated interest rate			6.375%
Interest expense			$ 35,700,000	36,700,000	$ 36,300,000
Debt Issuance Costs, Gross										$ 25,100,000
Senior Notes | 6.375% Senior Secured Notes due March 2025 (2025 Notes) | Open Market Purchase
Debt Instrument [Line Items]
Retirement of Debt			117,800,000
Senior Notes | 6.375% Senior Secured Notes due March 2025 (2025 Notes) | Debt for Equity Exchange
Debt Instrument [Line Items]
Proceeds from common stock issuances, net of costs			$ 47,200,000
Senior Notes | 6.375% Senior Secured Notes due March 2025 (2025 Notes) | Geographic Distribution, Domestic
Debt Instrument [Line Items]
Debt Instrument, Collateral, Capital Stock, Percent			100.00%
Senior Notes | 6.375% Senior Secured Notes due March 2025 (2025 Notes) | Geographic Distribution, Foreign
Debt Instrument [Line Items]
Debt Instrument, Collateral, Nonvoting Capital Stock, Percent			100.00%
Senior Notes | 6.375% Senior Secured Notes due March 2025 (2025 Notes) | Effect of Plan
Debt Instrument [Line Items]
Debt principal amount										$ 500,000,000
Senior Notes | 10.00% Senior Secured Notes Due 2024 (New Co-Issuer Notes)
Debt Instrument [Line Items]
Debt principal amount	193,900,000
Stated interest rate			10.00%
Long-term debt			$ 193,900,000	0
Debt covenant, liquidity attributable to co-issuers limit (minimum)	$ 60,000,000
Debt secured liens term, percentage of capital stock	100.00%
Interest and Debt Expense			$ 19,600,000
Debt Issuance Costs, Gross	$ 5,600,000
Senior Notes | 8.500% Senior Secured Notes due 2024 (New Peabody Notes)
Debt Instrument [Line Items]
Debt principal amount	195,100,000
Stated interest rate			8.50%
Long-term debt			$ 62,600,000	0
Interest rate per annum paid-in-kind			2.50%
Net (gain) loss on early debt extinguishment			$ (3,500,000)
Interest and Debt Expense			12,900,000
Debt Issuance Costs, Gross	5,700,000
Paid-in-Kind Interest			2,900,000
Debt exchange offer, required purchase amount (up to)			$ 22,400,000
Debt exchange offer, required purchase, percentage of accreted value			80.00%
Senior Notes | 8.500% Senior Secured Notes due 2024 (New Peabody Notes) | Open Market Purchase
Debt Instrument [Line Items]
Retirement of Debt			$ 91,400,000
Senior Notes | 8.500% Senior Secured Notes due 2024 (New Peabody Notes) | Debt for Equity Exchange
Debt Instrument [Line Items]
Proceeds from common stock issuances, net of costs			21,600,000
Senior Notes | 8.500% Senior Secured Notes due 2024 (New Peabody Notes) | Subsequent Event
Debt Instrument [Line Items]
Debt exchange offer, required purchase amount (up to)							$ 38,600,000
Debt exchange offer, required purchase, percentage of accreted value							94.94%
Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Interest expense			12,800,000	15,600,000	22,200,000
Original issue discount and deferred finance costs				10,400,000					37,300,000
Debt instrument, periodic payment			1,000,000
Repayments of debt						$ 500,000,000
Payment for debt extinguishment or debt prepayment cost		$ 46,000,000
Term Loan | Successor Credit Agreement | Effect of Plan
Debt Instrument [Line Items]
Debt principal amount									$ 950,000,000
Term Loan | Senior Secured Term Loan Due 2024
Debt Instrument [Line Items]
Debt amount incurred	206,000,000
Long-term debt			206,000,000.0	0
Interest and Debt Expense			20,500,000
Debt Issuance Costs, Gross	7,100,000
Term Loan | Senior Secured Term Loan Due 2025
Debt Instrument [Line Items]
Long-term debt			322,800,000
Term Loan | Senior Secured Term Loan Due 2025 | Open Market Purchase
Debt Instrument [Line Items]
Retirement of Debt			61,700,000
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt			0	216,000,000.0
Revolving Credit Facility | 2017 Revolver
Debt Instrument [Line Items]
Interest expense			1,400,000	$ 15,900,000	$ 6,200,000
2019 Revolver commitments, matures 2020	0
6.000% Senior Secured Notes due March 2022 (2022 Notes)
Debt Instrument [Line Items]
Net (gain) loss on early debt extinguishment			$ 0
London Interbank Offered Rate (LIBOR) | Term Loan | Successor Credit Agreement
Debt Instrument [Line Items]
Basis spread on variable rate			2.75%
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Repayments of lines of credit	10,000,000
Letter of Credit | Line of Credit
Debt Instrument [Line Items]
Debt amount incurred	324,000,000
Revolving credit facility, fee on unused borrowings			6.00%
Debt covenant, unrestricted subsidiaries' liquidity	200,000,000
Refinancing transactions, principal repurchase basis	4
Refinancing transactions, principal amount basis for purchase	$ 1
Refinancing transactions, debt repurchases period	30 days
Interest and Debt Expense			$ 21,900,000
Debt Issuance Costs, Gross	$ 4,100,000
Commitment fee percentage			0.50%
Debt covenant, aggregate liquidity at the end of each quarter	$ 125,000,000