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Summary of Significant Accounting Policies (Details) - USD ($) |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Jan. 29, 2021 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Mar. 31, 2022 | Mar. 01, 2022
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Corporate Hedging |  | From time to time, the Company may utilize various types of derivative instruments to manage its exposure to risks in the normal course of business, including (1) foreign currency exchange rate risk and the variability of cash flows associated with forecasted Australian dollar expenditures made in its Australian mining platform, (2) price risk of fluctuating coal prices related to forecasted sales or purchases of coal, or changes in the fair value of a fixed price physical sales contract, (3) price risk and the variability of cash flows related to forecasted diesel fuel purchased for use in its operations and (4) interest rate risk on long-term debt. These risk management activities are actively monitored for compliance with the Company’s risk management policies. On a limited basis, the Company engages in the direct and brokered trading of coal and freight-related contracts. Except those contracts for which the Company has elected to apply a normal purchases and normal sales exception, all derivative coal trading contracts are accounted for at fair value. The Company had no diesel fuel or interest rate derivatives in place as of December 31, 2022. |  |  |  |
Income tax (benefit) provision |  | $ (38,800,000) | $ 22,800,000 | $ 8,000,000.0 |  |
Accounts receivable, payment term |  | 30 days |  |  |  |
Interest costs capitalized |  | $ 0 | 0 | 0 |  |
Royalty Expense |  | $ 450,000,000 | 263,000,000 | 214,700,000 |  |
Lease term |  | 10 years |  |  |  |
Minimum annual production of federal coal mining leases on original amount |  | 1.00% |  |  |  |
Monthly federal royalties payable from sale using surface mining methods |  | 12.50% |  |  |  |
Monthly federal royalties payable of production using underground mining methods |  | 8.00% |  |  |  |
Equity method investment |  | $ 0 | 0 | 0 |  |
Impairment of investment in equity security |  | 0 | 0 | 1,700,000 |  |
Restructuring charges for voluntary and involuntary workforce reductions |  | 2,900,000 | 8,300,000 | 37,900,000 |  |
Restructuring charges |  | 800,000 |  |  |  |
Foreign currency remeasurement gain (loss) |  | (2,700,000) | (3,100,000) | (4,000,000) |  |
Foreign currency translation adjustment |  | 1,600,000 | 1,000,000.0 | (6,100,000) |  |
Asset impairment |  | 11,200,000 | 0 | 1,487,400,000 |  |
Asset impairment charges related to long-lived assets |  | $ 9,500,000 | $ 0 | $ 1,487,400,000 |  |
Letter of Credit |  |  |  |  |  |
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Stated interest rate |  | 0.75% |  |  |  |
Line of Credit | Letter of Credit |  |  |  |  |  |
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Debt amount incurred | $ 324,000,000 |  |  |  |  |
Revolving credit facility, fee on unused borrowings |  | 6.00% |  |  |  |
Commitment fee percentage |  | 0.50% |  |  |  |
Debt covenant, aggregate liquidity at the end of each quarter | $ 125,000,000 | $ 125,000,000 |  |  |  |
Senior Notes | 3.250% Convertible Senior Notes due March 2028 |  |  |  |  |  |
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Stated interest rate |  | 3.25% |  |  |  |
Debt principal amount |  |  |  |  | $ 320,000,000 | $ 320,000,000
Middlemount |  |  |  |  |  |
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Ownership percentage of equity method investment |  | 50.00% |  |  |  |
Minimum | Machinery and equipment | Buildings and improvements |  |  |  |  |  |
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Useful life |  | 1 year |  |  |  |
Maximum | Land and coal interests |  |  |  |  |  |
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Useful life |  | 30 years |  |  |  |
Maximum | Machinery and equipment | Buildings and improvements |  |  |  |  |  |
Summary of Significant Accounting Policies Textuals |  |  |  |  |  |
Useful life |  | 30 years |  |  |  |

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