Restructuring Costs (Details) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2021 USD ($)
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			$ 181
Restructuring expense	$ 17	$ 31	83	$ 128
Restructuring utilized/paid			84
Ending restructuring liability	180		$ 180
Total number of employee workforce reductions			1,700
Cost of sales and selling, general, and administrative expenses [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	4	9	$ 7	9
Severance and benefits [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			176
Restructuring expense			71
Restructuring utilized/paid			71
Ending restructuring liability	176		176
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			5
Restructuring expense			12
Restructuring utilized/paid			13
Ending restructuring liability	4		4
Automation Solutions [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	12	23	76	106
Commercial & Residential Solutions [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	4	7	6	17
Climate Technologies [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	3	2	4	9
Tools & Home Products [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	1	5	2	8
Corporate [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	$ 1	$ 1	$ 1	$ 5
Forecast [Member]
Restructuring Reserve [Roll Forward]
Expected fiscal year restructuring expense					$ 200