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Assets and Liabilities, at Fair Value - Narrative (Details) - USD ($) | Jul. 08, 2025 | Jun. 30, 2025 | Sep. 30, 2024 | Mar. 01, 2024
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Senior Secured Notes due 2031 |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Carrying value |  | $ 543,900,000 | $ 543,100,000 |
Senior Secured Notes due 2031 | Senior Notes |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  | 7.875%
Debt instrument, face amount |  |  |  | $ 550,000,000
Senior Secured Notes due 2031 | Senior Notes | Level 2 |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Long-term debt, fair value |  | $ 576,500,000 |  |
Senior Secured Notes due 2032 | Senior Notes | R.J. O’Brien | Subsequent Event |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Debt instrument, interest rate, stated percentage | 6.875% |  |  |
Debt instrument, face amount | $ 625,000,000 |  |  |

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