Restructuring and Impairment Costs (Details) $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($) employee	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2019 USD ($) plant employee	Jun. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Underspend						$ 9		$ (7)
Restructuring and impairment costs	$ 15			$ 57		$ 159	$ 372
Number of positions eliminated to date | employee	8,200					8,200
Number of positions eliminated | employee						5,400
Number of plants expected to close | plant						17
Number of plants closed | plant						15
Fixed asset impairment charges		$ 66
Impairment charges on long-lived assets held-for-sale			$ 6	$ 52
Goodwill impairment charge					$ 299
2019 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross						$ 96
2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross								71
Underspend						(9)
2018 Restructuring Plan | Employee Severance and Termination Benefits
Restructuring Cost and Reserve [Line Items]
Underspend						(9)
2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs									$ 46
2017 Restructuring Plan | Employee Severance and Termination Benefits
Restructuring Cost and Reserve [Line Items]
Underspend						2
2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Underspend								(20)
Restructuring and impairment costs										$ 332
2016 Restructuring Plan | Employee Severance and Termination Benefits
Restructuring Cost and Reserve [Line Items]
Underspend								(20)
Fixed Assets
Restructuring Cost and Reserve [Line Items]
Fixed asset impairment charges		62
Customer relationships
Restructuring Cost and Reserve [Line Items]
Fixed asset impairment charges		4
EMEA
Restructuring Cost and Reserve [Line Items]
Fixed asset impairment charges		55
EMEA | 2019 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross						76
EMEA | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross								52
EMEA | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs									34
EMEA | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs										298
Americas
Restructuring Cost and Reserve [Line Items]
Fixed asset impairment charges		$ 11
Americas | 2019 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross						13
Americas | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross								9
Americas | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs									7
Americas | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs										32
Asia | 2019 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross						$ 7
Asia | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs, gross								$ 10
Asia | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs									$ 5
Asia | 2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs										$ 2