Business Segment Information Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 4,151	$ 4,147
Reportable Geographical Components [Member]
Disaggregation of Revenue [Line Items]
Net sales	4,155	4,137
Reportable Geographical Components [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	2,273	2,312
Reportable Geographical Components [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	1,173	1,106
Reportable Geographical Components [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	709	719
Reportable Geographical Components [Member] | Automation Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	2,852	2,799
Reportable Geographical Components [Member] | Automation Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	1,410	1,405
Reportable Geographical Components [Member] | Automation Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	896	841
Reportable Geographical Components [Member] | Automation Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	546	553
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,303	1,338
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	863	907
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	277	265
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 163	$ 166