Business Segments (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Net sales	$ 4,791		$ 4,431	$ 9,264	$ 8,592
Earnings	811		737	1,986	1,300
Interest expense	(52)		(38)	(90)	(78)
Gain from periodic distribution from retained subordinated interest in Vertiv (VRT)	0	$ 453	0	453	0
Operating Segments [Member] | Automation Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	2,937		2,793	5,742	5,485
Earnings	556		471	1,082	832
Operating Segments [Member] | Commercial & Residential Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	1,857		1,645	3,528	3,121
Earnings	365		357	664	667
Operating Segments [Member] | Climate Technologies [Member]
Segment Reporting Information [Line Items]
Net sales	1,341		1,160	2,504	2,191
Earnings	262		245	454	457
Operating Segments [Member] | Tools & Home Products [Member]
Segment Reporting Information [Line Items]
Net sales	516		485	1,024	930
Earnings	103		112	210	210
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Stock compensation	(50)		(61)	(91)	(125)
Unallocated pension and postretirement costs	25		23	51	47
Interest expense	(52)		(38)	(90)	(78)
Corporate and other [Member]
Segment Reporting Information [Line Items]
Earnings	(33)		(15)	(83)	(43)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	$ (3)		$ (7)	$ (6)	$ (14)