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Accounting Policies - Narrative (Details) $ in Millions | 9 Months Ended |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2025 USD ($) | Dec. 31, 2024 USD ($) | Sep. 30, 2024 | Apr. 30, 2024 | Mar. 31, 2024 | Oct. 31, 2021 | Mar. 31, 2021 | Apr. 30, 2019
Inventories |  |  |  |  |  |  |  |
Materials and supplies inventory | $ 148.4 | $ 167.5 |  |  |  |  |  |
Hydrocarbons inventory | $ 16.0 | $ 3.4 |  |  |  |  |  |
Facility |  |  |  |  |  |  |  |
Cash, Cash Equivalents and Restricted Cash |  |  |  |  |  |  |  |
Debt cover ratio | 4.0 | 2.54 |  | 2.50 |  |  |  |
Facility Interest or Senior Notes |  |  |  |  |  |  |  |
Cash, Cash Equivalents and Restricted Cash |  |  |  |  |  |  |  |
Period for contractual future interest payments | 6 months |  |  |  |  |  |  |
7.125% Senior Notes | Senior Notes |  |  |  |  |  |  |  |
Cash, Cash Equivalents and Restricted Cash |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  |  |  | 7.125%
7.750% Senior Notes | Senior Notes |  |  |  |  |  |  |  |
Cash, Cash Equivalents and Restricted Cash |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  | 7.75% |  |
7.500% Senior Notes | Senior Notes |  |  |  |  |  |  |  |
Cash, Cash Equivalents and Restricted Cash |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  |  |  |  |  | 7.50% |
8.750% Senior Notes | Senior Notes |  |  |  |  |  |  |  |
Cash, Cash Equivalents and Restricted Cash |  |  |  |  |  |  |  |
Interest rate (as a percent) |  |  | 8.75% |  |  |  |  |
3.125% Convertible Senior Notes | Senior Notes |  |  |  |  |  |  |  |
Cash, Cash Equivalents and Restricted Cash |  |  |  |  |  |  |  |
Interest rate (as a percent) | 3.125% | 3.125% |  |  | 3.125% |  |  |

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