Business Segments Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 4,162	$ 4,570	$ 8,313	$ 8,717
Reportable Geographical Components [Member]
Disaggregation of Revenue [Line Items]
Net sales	4,167	4,571	8,322	8,708
Reportable Geographical Components [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	2,383	2,605	4,656	4,917
Reportable Geographical Components [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	1,065	1,195	2,238	2,301
Reportable Geographical Components [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	719	771	1,428	1,490
Reportable Geographical Components [Member] | Automation Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	2,709	3,010	5,561	5,809
Reportable Geographical Components [Member] | Automation Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	1,346	1,523	2,756	2,928
Reportable Geographical Components [Member] | Automation Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	830	910	1,726	1,751
Reportable Geographical Components [Member] | Automation Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	533	577	1,079	1,130
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member]
Disaggregation of Revenue [Line Items]
Net sales	1,458	1,561	2,761	2,899
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Americas
Disaggregation of Revenue [Line Items]
Net sales	1,037	1,082	1,900	1,989
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Asia, Middle East & Africa
Disaggregation of Revenue [Line Items]
Net sales	235	285	512	550
Reportable Geographical Components [Member] | Commercial & Residential Solutions [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 186	$ 194	$ 349	$ 360