Income Taxes - Deferred Income Taxes (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Compensation and benefits, assets	$ 426	$ 430
Loss and credit carryforwards, assets	2,352	2,185
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves	362	133
Deferred Tax Assets, Tax Deferred Expense, Capitalized Research And Development Costs	243	63
Other, assets	531	524
Deferred income taxes, assets, gross	3,914	3,335
Valuation allowance, assets	(2,272)	(2,093)
Deferred income taxes, assets	1,642	1,242
Property and equipment, liabilities	409	412
Deferred Tax Liabilities, Other Finite-Lived Assets	1,858	2,064
Other, liabilities	183	260
Deferred income taxes, liabilities, gross	2,450	2,736
Deferred income taxes, liabilities	$ 2,450	$ 2,736