Significant Restructuring Costs Change in Restructuring Reserve - 2018 Restructuring Plan (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	$ 0	$ 158	$ 99	$ 78	$ 158	$ 177
2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		158			158
Restructuring Reserve, Settled without Cash		(30)
Restructuring Reserve	119	128			119
Payments for Restructuring	(9)
Employee Severance | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		125
Restructuring Reserve, Settled without Cash		0
Restructuring Reserve	117	125			117
Payments for Restructuring	(8)
Fixed Asset Impairment | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		30
Restructuring Reserve, Settled without Cash		(30)
Restructuring Reserve	0	0			0
Payments for Restructuring	0
Other Restructuring | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs		3
Restructuring Reserve, Settled without Cash		0
Restructuring Reserve	2	$ 3			2
Payments for Restructuring	$ (1)
Global Products | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					76
Building Solutions EMEA/LA | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					32
Corporate Segment | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					24
Building Solutions Asia Pacific | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					14
Building Solutions North America | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					8
Power Solutions | 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs					$ 4