Restructuring and Impairment Costs -Narrative (Details) employee in Thousands, $ in Millions	12 Months Ended
	Sep. 30, 2021 USD ($) employee plant	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 115	$ 237
Restructuring and impairment costs	21	238	$ 176
Restructuring reserves	$ (136)	(80)	(108)
Restructuring charges recovered			6
Number of positions eliminated to date | employee	18
Number of positions eliminated | employee	15
Number of plants expected to close | plant	25
Number of plants closed | plant	19
2021 restructuring plan
Restructuring Cost and Reserve [Line Items]
Noncash adjustment—underspend	$ 16
Payments for restructuring	5
2021 restructuring plan | Employee Severance and Termination Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring reserve		27
Payments for restructuring	5
2021 restructuring plan | EMEA
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	23
2021 restructuring plan | Americas
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	3
2021 restructuring plan | Asia
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	1
2020 restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		205
Noncash adjustment—underspend		20
Payments for restructuring	87	35
2020 restructuring plan | Employee Severance and Termination Benefits
Restructuring Cost and Reserve [Line Items]
Payments for restructuring	87	35
2020 restructuring plan | EMEA
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		175
2020 restructuring plan | Americas
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		20
2020 restructuring plan | Asia
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		10
2019 restructuring plan
Restructuring Cost and Reserve [Line Items]
Noncash adjustment—underspend	(2)	(7)
Restructuring and impairment costs			105
Noncash adjustment—underspend			16
Restructuring reserves			9
Payments for restructuring	24	30	32
2019 restructuring plan | Employee Severance and Termination Benefits
Restructuring Cost and Reserve [Line Items]
Noncash adjustment—underspend	0	(7)
Payments for restructuring	24	$ 30	32
2019 restructuring plan | EMEA
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			81
2019 restructuring plan | Americas
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			16
2019 restructuring plan | Asia
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			$ 8
Restructuring plan 2018, 2017 & 2016
Restructuring Cost and Reserve [Line Items]
Payments for restructuring	20
2018 restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	3
2017 restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	2
2016 restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 2