Pension and Postretirement Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain	$ (42)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0	$ 1
Expected return on plan assets	(2)	(2)
Amortization of prior service credit	(1)	(1)
Net periodic benefit credit	(3)	(2)
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	10	11
Expected return on plan assets	(41)	(42)
Net actuarial gain	(42)	0
Settlement (gain) loss	(1)	0
Net periodic benefit credit	(74)	(31)
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	7
Interest cost	10	8
Expected return on plan assets	(21)	(28)
Net periodic benefit credit	$ (5)	$ (13)