Income Tax - Effective Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
(Provision) benefit for income taxes	$ (47)	$ (29)	$ (81)	$ (49)
Effective tax rate	33.00%	26.00%	34.00%	25.00%