Employee Benefit Plans - Net Periodic Defined Benefit Pension Costs (Detail) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
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]
Service cost						$ 1
Interest cost				$ 1		3
Expected return on plan assets				(1)		(3)
Settlement charge					$ 6
Net periodic benefit (credit) cost					6	1
Pension Benefits [Member] | Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1			1	4	4
Interest cost				1	2	3
Expected return on plan assets	(2)			(2)	(7)	(7)
Amortization of prior service cost	2				2
Amortization of actuarial loss	1			1	2	2
Settlement charge	1				1
Net periodic benefit (credit) cost	$ 3			$ 1	$ 4	$ 2