Business Segment Information Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Net sales	$ 4,147	$ 3,816
Reportable Geographical Components [Member]
Disaggregation of Revenue [Line Items]
Net sales	4,137	3,824
Reportable Geographical Components [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	2,312	2,064
Reportable Geographical Components [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	1,106	1,138
Reportable Geographical Components [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	719	622
Reportable Geographical Components [Member] | Automation Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	2,799	2,572
Reportable Geographical Components [Member] | Automation Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	1,405	1,286
Reportable Geographical Components [Member] | Automation Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	841	790
Reportable Geographical Components [Member] | Automation Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	553	496
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,338	1,252
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	907	778
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	265	348
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 166	$ 126