Restructuring and Related Costs - Schedule of Restructuring Reserve by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Restructuring Cost and Reserve [Line Items]
Restructuring costs and asset impairment charges	$ 254	$ 418	$ 293	$ 763
Various 2023 Restructuring Plans
Restructuring Cost and Reserve [Line Items]
Restructuring costs and asset impairment charges	24		63		$ 276
Building Solutions North America | Various 2023 Restructuring Plans
Restructuring Cost and Reserve [Line Items]
Restructuring costs and asset impairment charges	0		4
Building Solutions EMEA/LA | Various 2023 Restructuring Plans
Restructuring Cost and Reserve [Line Items]
Restructuring costs and asset impairment charges	0		13
Building Solutions Asia Pacific | Various 2023 Restructuring Plans
Restructuring Cost and Reserve [Line Items]
Restructuring costs and asset impairment charges	3		3
Global Products | Various 2023 Restructuring Plans
Restructuring Cost and Reserve [Line Items]
Restructuring costs and asset impairment charges	15		36
Corporate | Various 2023 Restructuring Plans
Restructuring Cost and Reserve [Line Items]
Restructuring costs and asset impairment charges	$ 6		$ 7