Employee Benefit Plans - Net Periodic Defined Benefit Pension Costs (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	$ 6	$ 3
Pension Benefits [Member] | U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost			$ 1
Expected return on plan assets			(1)
Settlement charge	6
Net periodic benefit (credit) cost	6
Pension Benefits [Member] | Foreign Plans [Member]
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		1
Net periodic benefit (credit) cost	$ 1		$ 1