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v3.24.3

Share-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2022 | Mar. 11, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Percentage of vesting in first anniversary | 30.00% |  |  |
Percentage of vesting in second anniversary | 30.00% |  |  |
Percentage of vesting in third anniversary | 40.00% |  |  |
Net share-based compensation expense | $ 23 | $ 18 | $ 22 |
Tax benefits from the exercise of stock options | $ 2 | 2 | 1 |
Stock Options [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Percentage of exercise price equal to market price on the date of grant | 100.00% |  |  |
Vesting period (in years) | 3 years |  |  |
Expiration period, years | 10 years |  |  |
Unrecognized compensation cost | $ 3 |  |  |
Weighted-average period, years | 1 year |  |  |
Options outstanding, aggregate intrinsic value | $ 76 |  |  |
Options exercisable, aggregate intrinsic value | 76 |  |  |
Intrinsic value of options exercised | 17 | 2 | 4 |
Cash received from exercises | 20 | $ 4 | $ 6 |
Tax benefits from the exercise of stock options | $ 2 |  |  |
Stock Options, Weighted Average Grant Date Fair Value, Granted | $ 27.42 | $ 26.28 | $ 15.95 |
Restricted Stock Units [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Vesting period (in years) | 3 years |  |  |
Unrecognized compensation cost | $ 22 |  |  |
Weighted-average period, years | 1 year |  |  |
Estimated weighted average grant date fair value | $ 75.98 | $ 73.68 | $ 58.72 |
Intrinsic value of restricted stock units vested | $ 37 | $ 20 | $ 13 |
Restricted Stock [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Vesting period (in years) | 3 years |  |  |
Supplemental 401(k) Plan [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Supplemental retirement savings plan, aggregate value of the accounts, shares | 117,000 | 113,000 |  |
2017 Long-Term Incentive Plan [Member] | Maximum [Member] |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |
Common stock, authorized shares |  |  |  | 8,625,000

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