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Long-term Debt - Schedule of Debt (Details) | 3 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Dec. 31, 2023 USD ($) buyer $ / shares shares | Mar. 31, 2022 USD ($) shares | Dec. 31, 2023 USD ($) buyer $ / shares shares | Dec. 31, 2022 USD ($) shares | Dec. 31, 2021 USD ($) shares | Mar. 01, 2025 USD ($) | Mar. 07, 2022 USD ($) | Mar. 01, 2022 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Finance Lease, Liability | $ 22,300,000 |  | $ 22,300,000 | $ 23,600,000 |  |  |  |
Less: Debt issuance costs | (8,100,000) |  | (8,100,000) | (9,800,000) |  |  |  |
Debt and Lease Obligation, Net | 334,200,000 |  | 334,200,000 | 333,800,000 |  |  |  |
Less: Current portion of long-term debt | 13,500,000 |  | 13,500,000 | 13,200,000 |  |  |  |
Long-Term Debt and Lease Obligation, Total | $ 320,700,000 |  | 320,700,000 | 320,600,000 |  |  |  |
Interest expense |  |  | 59,800,000 | 140,300,000 | $ 183,400,000 |  |  |
Financial Assurance Instruments |  |  | 38,200,000 | 53,300,000 | 51,100,000 |  |  |
Interest Paid, Capitalized, Investing Activities |  |  | $ 61,900,000 | $ 118,500,000 | 174,900,000 |  |  |
Common Stock, shares authorized (in shares) | shares | 450,000,000.0 |  | 450,000,000.0 | 450,000,000.0 |  |  |  |
Proceeds from common stock issuances, net of costs |  |  | $ 0 | $ 222,000,000.0 | 269,800,000 |  |  |
Common Stock, shares issued (in shares) | shares | 188,600,000 |  | 188,600,000 | 187,100,000 |  |  |  |
Net loss (gain) on early debt extinguishment |  |  | $ (8,800,000) | $ (57,900,000) | 33,200,000 |  |  |
Noncash interest expense, net |  |  | $ 4,600,000 | $ 17,700,000 | $ 21,300,000 |  |  |
Letter of Credit |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Stated interest rate | 0.75% |  | 0.75% |  |  |  |  |
Exit facility, maximum borrowing capacity | $ 250,000,000 |  | $ 250,000,000 |  |  |  |  |
Common Stock |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Common Stock, shares authorized (in shares) | shares | 450,000,000 |  | 450,000,000 |  |  |  |  |
At Market Issuance |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Common Stock, shares issued (in shares) | shares | 0 |  | 0 | 10,100,000 | 24,800,000 |  |  |
Debt for Equity Exchange |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Common Stock, shares issued (in shares) | shares | 0 |  | 0 | 0 | 10,000,000.0 |  |  |
3.250% Convertible Senior Notes due March 2028 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Trading Days | buyer | 20 |  |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Consecutive Trading Days | buyer | 30 |  |  |  |  |  |  |
Indebtedness |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Interest expense |  |  | $ 21,600,000 | $ 87,000,000.0 | $ 132,300,000 |  |  |
10.000% Senior Secured Notes due December 2024 and Senior Secured Term Loan due 2024 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Payment for debt extinguishment or debt prepayment cost |  |  |  | 18,500,000 |  |  |  |
8.500% Senior Secured Notes due December 2024 and 6.375% Senior Secured Notes due March 2025 [Domain] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Net loss (gain) on early debt extinguishment |  | $ 23,000,000 |  |  |  |  |  |
10.00% Revolving Credit Facility maturing 2025 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Exit facility, maximum borrowing capacity |  | 225,000,000 |  |  |  |  |  |
Proceeds from Issuance or Sale of Equity |  | $ 222,000,000 |  |  |  |  |  |
10.00% Revolving Credit Facility maturing 2025 | At Market Issuance | Common Stock |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Sale of Stock, Number of Shares Issued in Transaction | shares |  | 10,100,000 |  |  |  |  |  |
Senior Notes | 6.000% Senior Secured Notes due March 2022 (2022 Notes) |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt repurchase, amount |  | $ 23,100,000 |  |  |  |  |  |
Senior Notes | 6.375% Senior Secured Notes due March 2025 (2025 Notes) |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Payment for debt extinguishment or debt prepayment cost |  |  |  | 66,100,000 |  |  |  |
Debt repurchase, amount |  | 257,400,000 |  | 257,400,000 |  |  |  |
Senior Notes | 8.500% Senior Secured Notes due 2024 (New Peabody Notes) |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt repurchase, amount |  | 62,600,000 |  | 62,500,000 |  |  |  |
Senior Notes | 3.250% Convertible Senior Notes due March 2028 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Stated interest rate | 3.25% |  | 3.25% |  |  |  |  | 3.25%
Long-term debt | $ 320,000,000.0 |  | $ 320,000,000.0 | 320,000,000.0 |  |  |  |
Debt principal amount |  |  |  |  |  |  |  | $ 320,000,000
Debt Issuance Costs, Gross |  | $ 11,200,000 |  |  |  |  |  |
Common Stock, Excess of the Conversion Price, Percentage | 130.00% |  | 130.00% |  |  |  |  |
Debt Instrument, Convertible, Threshold Consecutive Trading Days | buyer |  |  | 30 |  |  |  |  |
Debt Instrument, Principle Amount | $ 1,000 |  | $ 1,000 |  |  |  |  |
Principle Amount, Percentage | 98.00% |  | 98.00% |  |  |  |  |
Debt Instrument, Convertible, Conversion Price | $ / shares | $ 19.85 |  | $ 19.85 |  |  |  |  |
Senior Notes | 3.250% Convertible Senior Notes due March 2028 | Minimum |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Consecutive Trading Days | buyer | 20 |  |  |  |  |  |  |
Senior Notes | 3.250% Convertible Senior Notes due March 2028 | Subsequent Event |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Principle Amount, Percentage |  |  |  |  |  | 100.00% |  |
Aggregate Principle Amount, Notes Outstanding |  |  |  |  |  | $ 75,000,000 |  |
Senior Notes | 10.000% Senior Secured Notes due December 2024 and Senior Secured Term Loan due 2024 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Payment for debt extinguishment or debt prepayment cost |  |  |  | 28,100,000 |  |  |  |
Senior Notes | 10.00% Revolving Credit Facility maturing 2025 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Stated interest rate |  |  |  |  |  |  | 10.00% |
Exit facility, maximum borrowing capacity |  |  |  |  |  |  | $ 150,000,000 |
Term Loan | Senior Secured Term Loan Due 2024 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Payment for debt extinguishment or debt prepayment cost |  |  |  | 2,900,000 |  |  |  |
Term Loan | Senior Secured Term Loan Due 2025 |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Payment for debt extinguishment or debt prepayment cost |  |  |  | 276,200,000 |  |  |  |
Debt repurchase, amount |  |  |  | $ 44,100,000 |  |  |  |

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