Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net sales	$ 4,431	$ 4,162	$ 8,592	$ 8,313
Earnings	737	689	1,300	1,112
Interest expense	(38)	(36)	(78)	(71)
Operating Segments [Member] | Automation Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	2,793	2,709	5,485	5,561
Earnings	471	391	832	701
Operating Segments [Member] | Commercial & Residential Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	1,645	1,458	3,121	2,761
Earnings	357	306	667	543
Operating Segments [Member] | Climate Technologies [Member]
Segment Reporting Information [Line Items]
Net sales	1,160	1,026	2,191	1,899
Earnings	245	217	457	368
Operating Segments [Member] | Tools & Home Products [Member]
Segment Reporting Information [Line Items]
Net sales	485	432	930	862
Earnings	112	89	210	175
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Stock compensation	(61)	38	(125)	(18)
Unallocated pension and postretirement costs	23	12	47	25
Interest expense	(38)	(36)	(78)	(71)
Corporate and other [Member]
Segment Reporting Information [Line Items]
Earnings	(15)	(22)	(43)	(68)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	$ (7)	$ (5)	$ (14)	$ (9)