Earnings per Share - Schedule of Weighted-Average Shares Outstanding (Details) - shares shares in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| Schedule Of Weighted Average Number Of Shares [Line Items] | ||||
| Basic weighted-average shares outstanding (in shares) | 46.5 | 48.0 | 48.3 | |
| Effect of dilutive securities (in shares) | 0.3 | 0.2 | 0.0 | 0.1 |
| Diluted weighted-average shares outstanding (in shares) | 46.8 | 48.2 | 46.5 | 48.4 |
| Option, RSE and PRSE awards | ||||
| Schedule Of Weighted Average Number Of Shares [Line Items] | ||||
| Effect of dilutive securities (in shares) | 0.3 | 0.2 | 0.0 | 0.1 |