Income Tax - Effective Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
(Provision) benefit for income taxes	$ (41)	$ (34)
Effective tax rate	28.00%	36.00%

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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+ Details