Business Segments (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 4,161	$ 4,151
Earnings	563	423
Interest expense	(40)	(35)
Operating Segments [Member] \| Automation Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	2,692	2,852
Earnings	361	310
Operating Segments [Member] \| Commercial & Residential Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	1,476	1,303
Earnings	310	237
Operating Segments [Member] \| Climate Technologies [Member]
Segment Reporting Information [Line Items]
Net sales	1,031	873
Earnings	212	151
Operating Segments [Member] \| Tools & Home Products [Member]
Segment Reporting Information [Line Items]
Net sales	445	430
Earnings	98	86
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Stock compensation	(64)	(56)
Unallocated pension and postretirement costs	24	13
Interest expense	(40)	(35)
Corporate and other [Member]
Segment Reporting Information [Line Items]
Earnings	(28)	(46)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	$ (7)	$ (4)

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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