Accounts Receivable Factoring and Securitization (Details) € in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 EUR (€)	Jun. 30, 2019 USD ($)	Sep. 30, 2018 EUR (€)	Sep. 30, 2018 USD ($)
Accounts Receivable Factoring And Securitization [Line Items]
Maximum limit for securitization financing arrangement						$ 110
Utilization of securitization financing arrangement						3		$ 57
Maximum limit for sale of eligible trade receivables					€ 210	313
Utilization of accounts receivable factoring facility under arrangement					198	294	€ 224	260
Costs associated with off balance sheet factoring arrangements	$ 2	$ 1	$ 5	$ 3
Committed U.S. accounts receivable securitization
Accounts Receivable Factoring And Securitization [Line Items]
Maximum limit for securitization financing arrangement						110
Utilization of securitization financing arrangement						3		57
Debt-to-EBITDA ratio			2.25
Committed U.S. accounts receivable securitization | Letter of Credit
Accounts Receivable Factoring And Securitization [Line Items]
Letters of credit outstanding						3		11
Committed Swedish factoring facility
Accounts Receivable Factoring And Securitization [Line Items]
Maximum limit for sale of eligible trade receivables					155	176
Utilization of accounts receivable factoring facility under arrangement					140	160	136	158
Liquidity commitment			364 days
Committed U.S. factoring facility (2)
Accounts Receivable Factoring And Securitization [Line Items]
Maximum limit for sale of eligible trade receivables						75
Utilization of accounts receivable factoring facility under arrangement						70	45	53
Uncommitted U.K. factoring facility
Accounts Receivable Factoring And Securitization [Line Items]
Maximum limit for sale of eligible trade receivables					25	28
Utilization of accounts receivable factoring facility under arrangement					10	11	8	9
Uncommitted Italy factoring facility
Accounts Receivable Factoring And Securitization [Line Items]
Maximum limit for sale of eligible trade receivables					30	34
Utilization of accounts receivable factoring facility under arrangement					30	34	24	28
Other uncommitted factoring facilities (4)
Accounts Receivable Factoring And Securitization [Line Items]
Utilization of accounts receivable factoring facility under arrangement					€ 18	$ 19	€ 11	$ 12