Share-Based Compensation - Schedule of Performance Shares Vested (Details) - Performance shares - USD ($) shares in Thousands, $ in Millions	12 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent payout	70.00%	0.00%	92.00%
Shares vested (in thousands) (in shares)	35	0	31
Total fair value of shares vested	$ 14	$ 0	$ 9

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details