Litigation, Claims and Contingencies - Summary of Asbestos Claims Activity (Details) - Claim Claim in Thousands |
9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Sep. 30, 2024 |
Sep. 30, 2023 |
Sep. 30, 2022 |
|
| Ashland [Member] | |||||
| Asbestos claims [Roll Forward] | |||||
| Open claims - beginning of year | 41 | 42 | 42 | 44 | 46 |
| New claims filed | 1 | 1 | 2 | 2 | 2 |
| Claims settled | 0 | 0 | (1) | (1) | (1) |
| Claims dismissed | (2) | (1) | (2) | (3) | (3) |
| Open claims - end of period | 40 | 42 | 41 | 42 | 44 |
| Hercules [Member] | |||||
| Asbestos claims [Roll Forward] | |||||
| Open claims - beginning of year | 12 | 12 | 12 | 11 | 12 |
| New claims filed | 1 | 1 | 1 | 1 | 1 |
| Claims dismissed | (1) | (1) | (1) | 0 | (2) |
| Open claims - end of period | 12 | 12 | 12 | 12 | 11 |