Business Segment Information Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 4,684	$ 4,456	$ 13,401	$ 12,520
Reportable Geographical Components [Member]
Disaggregation of Revenue [Line Items]
Net sales	4,687	4,462	13,395	12,540
Reportable Geographical Components [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	2,612	2,500	7,529	6,919
Reportable Geographical Components [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	1,283	1,256	3,584	3,602
Reportable Geographical Components [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	792	706	2,282	2,019
Reportable Geographical Components [Member] | Automation Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	3,025	2,870	8,834	8,213
Reportable Geographical Components [Member] | Automation Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	1,448	1,401	4,376	4,059
Reportable Geographical Components [Member] | Automation Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	970	917	2,721	2,575
Reportable Geographical Components [Member] | Automation Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	607	552	1,737	1,579
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,662	1,592	4,561	4,327
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	1,164	1,099	3,153	2,860
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	313	339	863	1,027
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 185	$ 154	$ 545	$ 440