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Financial Instruments, Guarantees With Off Balance Sheet Risk and Other Guarantees (Details) $ in Millions, $ in Millions | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2025 USD ($) | Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2025 AUD ($) | Nov. 03, 2025 | Dec. 31, 2024 AUD ($) | Feb. 13, 2023 USD ($) | Mar. 01, 2022 USD ($)
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Interest expense, net of capitalized interest | $ 43.9 | $ 46.9 | $ 59.8 |  |  |  |  |
Restricted cash included in “Restricted cash and collateral” | 709.2 | 682.2 |  |  |  |  |  |
Financial Instrument, Surety Bonds Amount | 997.2 |  |  |  |  |  |  |
Net loss on early debt extinguishment | 0.0 | 0.0 | 8.8 |  |  |  |  |
Restricted cash and collateral | 844.1 | 809.8 |  |  |  |  |  |
Cash-backed bank guarantee facilities | 208.7 |  |  |  |  |  |  |
Capitalized debt issuance costs related to Securitization Program | 1.8 |  |  |  |  |  |  |
Cash Collateral, Percentage of the aggregate amount of letters of credit outstanding if credit rating falls below threshold |  |  |  |  | 103.00% |  |  |
Surety Trust Account |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Restricted cash included in “Restricted cash and collateral” | 383.6 | 394.6 |  |  |  |  |  |
Collateralized letters of credit funding |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Restricted cash included in “Restricted cash and collateral” | 325.6 | 287.6 |  |  |  |  |  |
Deposits with Regulatory Authorities |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Deposits Assets | 134.9 | 127.6 |  | $ 201.0 |  | $ 205.0 |  |
Cash backed bank guarantees |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Restricted cash included in “Restricted cash and collateral” |  |  |  | $ 312.0 |  | $ 271.0 |  |
Asset Retirement Obligations |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Financial Instrument, Surety Bonds Amount | 908.8 |  |  |  |  |  |  |
Letters of credit outstanding, amount | 53.6 |  |  |  |  |  |  |
Surety Bonds and Letters of Credit Outstanding for Reclamation Support | 962.4 |  |  |  |  |  |  |
Letters of Credit in Support of Surety Bonds | (53.6) |  |  |  |  |  |  |
Total Obligations Supported, Net | 908.8 |  |  |  |  |  |  |
Other Obligations |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Financial Instrument, Surety Bonds Amount | 88.4 |  |  |  |  |  |  |
Letters of credit outstanding, amount | 59.0 |  |  |  |  |  |  |
Surety Bonds and Letters of Credit Outstanding for Other Support | 147.4 |  |  |  |  |  |  |
Letters of Credit in Support of Surety Bonds | (1.6) |  |  |  |  |  |  |
Total Obligations Supported, Net | 145.8 |  |  |  |  |  |  |
Asset Retirement and Other Obligations |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Financial Instrument, Surety Bonds Amount | 997.2 |  |  |  |  |  |  |
Letters of credit outstanding, amount | 112.6 |  |  |  |  |  |  |
Total Surety Bonds and Letters of Credit Outstanding | 1,109.8 |  |  |  |  |  |  |
Total Letters of Credit in Support of Surety Bonds | (55.2) |  |  |  |  |  |  |
Total Obligations Supported, Net | 1,054.6 |  |  |  |  |  |  |
Surety Bond |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Surety Agreement Liquidity Covenant, Amount | 400.0 |  |  |  |  |  |  |
Difference between penal sum of all surety bonds and amount of collateral posted in favor of surety providers | 487.3 |  |  |  |  |  |  |
Collateral amount held in trust accounts | 383.6 |  |  |  |  |  |  |
Collateral amount held as letters of credit | $ 126.3 |  |  |  |  |  |  |
Surety Bond | Maximum |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Debt Instrument Covenant, Net Leverage Ratio | 1.5 |  |  | 1.5 |  |  |  |
Debt Instrument, Collateral | 509.9 million |  |  |  |  |  |  |
Surety Bond | Minimum |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Debt Instrument Covenant, Net Leverage Ratio | 1.0 |  |  | 1.0 |  |  |  |
3.250% Convertible Senior Notes due March 2028 | Senior Notes |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Debt principal amount |  |  |  |  |  |  |  | $ 320.0
Stated interest rate | 3.25% |  |  | 3.25% |  |  |  |
Debt Instrument, Funded, Percent | 50.00% |  |  | 50.00% |  |  |  |
Accounts Receivable Securitization Program |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Exit facility, maximum borrowing capacity |  |  |  |  |  |  | $ 225.0 |
Interest expense, net of capitalized interest | $ 2.4 | 2.6 | 3.6 |  |  |  |  |
Accounts Receivable Securitization Program | Secured Debt |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate | 2.10% |  |  |  |  |  |  |
Long-term debt | $ 0.0 |  |  |  |  |  |  |
Interest expense, net of capitalized interest | 2.4 | $ 2.6 | 3.6 |  |  |  |  |
Accounts Receivable from Securitization | 96.0 |  |  |  |  |  |  |
Secured Debt | Accounts Receivable Securitization Program |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Letters of credit outstanding, amount | 63.4 |  |  |  |  |  |  |
Letter of Credit |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Exit facility, maximum borrowing capacity | $ 250.0 |  |  |  |  |  |  |
Cash Collateral, Percentage of the aggregate amount of letters of credit outstanding | 103.00% |  |  | 103.00% |  |  |  |
Stated interest rate | 0.75% |  |  | 0.75% |  |  |  |
Net loss on early debt extinguishment |  |  | $ 8.8 |  |  |  |  |
Letter of Credit | Maximum |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Transaction support agreements, additional collateral demands | $ 5.0 |  |  |  |  |  |  |
Collateralized Letter of Credit Agreement |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Letters of credit outstanding, amount | 114.6 |  |  |  |  |  |  |
Cash-collateralized Letters of Credit | $ 116.9 |  |  |  |  |  |  |
Letter of credit amendment |  |  |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |  |  |
Cash Collateral, Percentage of the aggregate amount of letters of credit outstanding |  |  |  |  | 102.00% |  |  |

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