Earnings per share - Narrative (Details) - shares shares in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Restricted Stock Units (RSUs) | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||||
| Antidilutive securities excluded from computation of earnings per share, amount | 1.1 | 0.7 | 1.1 | 0.7 |
| Performance Shares | ||||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||||
| Antidilutive securities excluded from computation of earnings per share, amount | 1.1 | 1.1 | 1.2 | 0.9 |