Significant Restructuring Costs Change in Restructuring Reserve - 2020 Restructuring Plan (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	$ 610			$ 235	$ 783	$ 235
Goodwill, Impairment Loss					424
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		$ 62
2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	186		$ 111		297
Payments for Restructuring	(29)	(25)	(8)
Restructuring Reserve, Settled without Cash	(42)		(54)
Restructuring Reserve	139	24	49		139
Employee Severance | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	142		54
Payments for Restructuring	(28)	(24)	(8)
Restructuring Reserve, Settled without Cash	0		0
Restructuring Reserve	136	22	46		136
Long-Lived Asset Impairment | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	42		54
Payments for Restructuring	0	0	0
Restructuring Reserve, Settled without Cash	(42)		(54)
Restructuring Reserve	0	0	0		0
Other Restructuring | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	2		3
Payments for Restructuring	(1)	(1)	0
Restructuring Reserve, Settled without Cash	0		0
Restructuring Reserve	3	$ 2	$ 3		3
Global Products
Restructuring Cost and Reserve [Line Items]
Goodwill, Impairment Loss					0
Global Products | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					136
Building Solutions Asia Pacific
Restructuring Cost and Reserve [Line Items]
Goodwill, Impairment Loss					0
Building Solutions Asia Pacific | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					49
Building Solutions EMEA/LA
Restructuring Cost and Reserve [Line Items]
Goodwill, Impairment Loss					0
Building Solutions EMEA/LA | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					43
Corporate Segment | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					5
Building Solutions North America
Restructuring Cost and Reserve [Line Items]
Goodwill, Impairment Loss	$ 424				424
Building Solutions North America | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					$ 64