Employee Benefit Plans - Net Periodic Defined Benefit Pension Costs (Detail) - Pension Benefits [Member] - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 1
Interest cost	1	1
Expected return on plan assets	$ (2)	(2)
Amortization of actuarial loss		1
Settlement charge		6
Net periodic benefit (credit) cost		$ 7