Benefit Plans (Detail) - Pension Plans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 22	$ 34	$ 46	$ 69
Interest cost	32	19	67	38
Expected return on plan assets	(35)	(46)	(73)	(94)
Amortization of prior service credit	(2)	(4)	(3)	(8)
Amortization of loss	15	15	32	31
Settlements	1	1	1	6
Net pension cost	$ 34	$ 18	$ 70	$ 42