Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Net sales	$ 4,697	$ 3,914	$ 13,289	$ 12,227
Earnings	784	458	2,084	1,570
Interest expense	(37)	(45)	(115)	(116)
Operating Segments [Member] | Automation Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	2,947	2,589	8,432	8,150
Earnings	521	311	1,353	1,012
Operating Segments [Member] | Commercial & Residential Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	1,757	1,327	4,878	4,088
Earnings	375	253	1,042	796
Operating Segments [Member] | Climate Technologies [Member]
Segment Reporting Information [Line Items]
Net sales	1,268	970	3,459	2,869
Earnings	274	195	731	563
Operating Segments [Member] | Tools & Home Products [Member]
Segment Reporting Information [Line Items]
Net sales	489	357	1,419	1,219
Earnings	101	58	311	233
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Stock compensation	(66)	(51)	(191)	(69)
Unallocated pension and postretirement costs	24	12	71	37
Interest expense	(37)	(45)	(115)	(116)
Corporate and other [Member]
Segment Reporting Information [Line Items]
Earnings	(33)	(22)	(76)	(90)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	$ (7)	$ (2)	$ (21)	$ (11)