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Earnings per Share - Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
Numerator: |  |
Net income | $ 85.1 | $ 69.1
Less: Allocation to participating securities | (2.7) | (2.4)
Net income allocated to common stockholders, basic | 82.4 | 66.7
Net income allocated to common stockholders, diluted | $ 82.4 | $ 66.7
Denominator: |  |
Common shares outstanding (in shares) | 30,976,042 | 30,233,107
Dilutive potential common shares outstanding: |  |
Share-based awards (in shares) | 1,468,730 | 1,041,200
Diluted weighted-average common shares (in shares) | 32,444,772 | 31,274,307

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