Restructuring and Impairment Costs - Changes in Reserve (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	$ 115
Noncash adjustment—underspend/other			$ 20
Restructuring reserve ending balance	70	$ 115
2022 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	20
Utilized—cash	(5)
Noncash adjustment—underspend/other	(1)
Restructuring reserve ending balance	14	20
2021 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	22
Utilized—cash	(15)
Noncash adjustment—underspend/other	(2)	16
Restructuring reserve ending balance	5	22
2020 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	77
Utilized—cash	(23)
Noncash adjustment—underspend/other	(12)
Restructuring reserve ending balance	42	77
2019 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	9
Utilized—cash	(4)
Noncash adjustment—underspend/other	(1)
Restructuring reserve ending balance	4	9
Employee Severance and Termination Benefits | 2022 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	20
Utilized—cash	(5)
Noncash adjustment—underspend/other	(1)
Restructuring reserve ending balance	14	20
Employee Severance and Termination Benefits | 2021 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	22
Utilized—cash	(15)
Noncash adjustment—underspend/other	(1)
Restructuring reserve ending balance	6	22
Employee Severance and Termination Benefits | 2020 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	75
Utilized—cash	(23)
Noncash adjustment—underspend/other	(6)
Restructuring reserve ending balance	46	75
Employee Severance and Termination Benefits | 2019 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	8
Utilized—cash	(4)
Noncash adjustment—underspend/other	(1)
Restructuring reserve ending balance	3	8
Currency Translation | 2021 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	0
Utilized—cash	0
Noncash adjustment—underspend/other	(1)
Restructuring reserve ending balance	(1)	0
Currency Translation | 2020 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	2
Utilized—cash	0
Noncash adjustment—underspend/other	(6)
Restructuring reserve ending balance	(4)	2
Currency Translation | 2019 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve beginning balance	1
Utilized—cash	0
Noncash adjustment—underspend/other	0
Restructuring reserve ending balance	$ 1	$ 1