Significant Restructuring and Impairment Costs (Detail) $ in Millions	9 Months Ended	12 Months Ended			24 Months Ended
	Jun. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) Employees	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2021 USD ($) Employees
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		$ 242	$ 783	$ 235
Number of employees to be severed | Employees					10,000
Restructuring and Related Cost, Number of Positions Eliminated, Inception to Date | Employees		7,800			7,800
Goodwill, Impairment Loss		$ 0	424
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)			62
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		24	5
2021 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		242
Payments for Restructuring		(79)
Restructuring Reserve, Settled without Cash		(98)
Restructuring Reserve		65			$ 65
Restructuring and Related Cost, Expected Cost		385			385
2021 Restructuring Plan | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		68
Payments for Restructuring		(28)
Restructuring Reserve, Settled without Cash		0
Restructuring Reserve		40			40
2021 Restructuring Plan | Fixed Asset Impairment
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		98
Payments for Restructuring		0
Restructuring Reserve, Settled without Cash		(98)
Restructuring Reserve		0			0
2021 Restructuring Plan | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		76
Payments for Restructuring		(51)
Restructuring Reserve, Settled without Cash		0
Restructuring Reserve		25			25
2020 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			297
Payments for Restructuring		(71)	(95)
Restructuring Reserve, Settled without Cash			(96)
Restructuring Reserve, Foreign Currency Translation Gain (Loss)			2
Restructuring Reserve		37	108		37
2020 Restructuring Plan [Member] | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			196
Payments for Restructuring		(69)	(92)
Restructuring Reserve, Settled without Cash			0
Restructuring Reserve, Foreign Currency Translation Gain (Loss)			2
Restructuring Reserve		37	106		37
2020 Restructuring Plan [Member] | Fixed Asset Impairment
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			96
Payments for Restructuring		0	0
Restructuring Reserve, Settled without Cash			(96)
Restructuring Reserve, Foreign Currency Translation Gain (Loss)			0
Restructuring Reserve		0	0		0
2020 Restructuring Plan [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			5
Payments for Restructuring		(2)	(3)
Restructuring Reserve, Settled without Cash			0
Restructuring Reserve, Foreign Currency Translation Gain (Loss)			0
Restructuring Reserve		0	2		$ 0
Building Solutions Asia Pacific | Building Technologies & Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		28	56
Goodwill, Impairment Loss		0	0
Building Solutions Asia Pacific | 2021 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		28
Building Solutions Asia Pacific | 2020 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			49
Corporate | 2021 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		24
Corporate | 2020 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			5
Building Solutions EMEA/LA | Building Technologies & Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		29	59
Goodwill, Impairment Loss		0	0
Building Solutions EMEA/LA | 2021 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		29
Building Solutions EMEA/LA | 2020 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			43
Building Solutions North America
Restructuring Cost and Reserve [Line Items]
Goodwill, Impairment Loss			424
Building Solutions North America | Building Technologies & Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		70	520
Goodwill, Impairment Loss	$ 424	0	424
Building Solutions North America | 2021 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		70
Building Solutions North America | 2020 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			64
Global Products | Building Technologies & Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		91	143	$ 235
Goodwill, Impairment Loss		0	0
Global Products | 2021 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		$ 91
Global Products | 2020 Restructuring Plan [Member] | Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs			$ 136