Restructuring (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2018
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			$ 65
Restructuring expense	$ 9	$ 13	24	$ 24
Restructuring paid			38
Ending restructuring liability	51		51
Severance and benefits [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			60
Restructuring expense			15
Restructuring paid			30
Ending restructuring liability	45		45
Lease and other contract terminations [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			4
Restructuring expense			2
Restructuring paid			2
Ending restructuring liability	4		4
Fixed Assets Write Downs [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			0
Restructuring expense			1
Restructuring paid			1
Ending restructuring liability	0		0
Vacant facility and other shutdown costs [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			1
Restructuring expense			2
Restructuring paid			1
Ending restructuring liability	2		2
Start-up and moving costs [Member]
Restructuring Reserve [Roll Forward]
Beginning restructuring liability			0
Restructuring expense			4
Restructuring paid			4
Ending restructuring liability	0		0
Automation Solutions [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	7	9	17	15
Commercial & Residential Solutions [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	2	3	7	8
Climate Technologies [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	2	3	7	7
Tools & Home Products [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	0	0	0	1
Corporate Segment [Member]
Restructuring Reserve [Roll Forward]
Restructuring expense	$ 0	$ 1	$ 0	$ 1
Scenario, Forecast [Member]
Restructuring Reserve [Roll Forward]
Expected fiscal year restructuring expense					$ 65