Income Taxes - Deferred Income Taxes (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Compensation and benefits, assets	$ 430	$ 524
Loss and credit carryforwards, assets	2,185	2,107
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves	133	191
Other, assets	524	549
Deferred income taxes, assets, gross	3,271	3,370
Valuation allowance, assets	(2,093)	(2,036)
Deferred income taxes, assets	1,178	1,334
Property and equipment, liabilities	412	400
Deferred Tax Liabilities, Other Finite-Lived Assets	2,002	2,161
Other, liabilities	260	123
Deferred income taxes, liabilities, gross	2,674	2,684
Deferred income taxes, liabilities	$ 2,674	$ 2,684