Significant Restructuring Costs Change in Restructuring Reserve - 2017 Restructuring Plan (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	$ 0	$ 154
2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				$ 367
Payments for Restructuring	(2)		$ (158)	(75)
Restructuring Reserve, Settled without Cash	(2)		(1)	(78)
Adjustment to restructuring reserves				25
Restructuring Reserve	73		80	239
Employee Severance | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				276
Payments for Restructuring	(2)		(152)	(75)
Restructuring Reserve, Settled without Cash	0		0	0
Adjustment to restructuring reserves				25
Restructuring Reserve	69		74	226
Fixed Asset Impairment | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				77
Payments for Restructuring	0		0	0
Restructuring Reserve, Settled without Cash	0		0	(77)
Adjustment to restructuring reserves				0
Restructuring Reserve	0		0	0
Other Restructuring | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				14
Payments for Restructuring	0		(6)	0
Restructuring Reserve, Settled without Cash	0		0	(1)
Adjustment to restructuring reserves				0
Restructuring Reserve	7		7	13
Currency Translation | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				0
Payments for Restructuring	0		0	0
Restructuring Reserve, Settled without Cash	(2)		(1)	0
Adjustment to restructuring reserves				0
Restructuring Reserve	(3)		$ (1)	0
Corporate Segment | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				166
Building Technologies & Solutions EMEA LA [Member] | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				74
Building Solutions North America | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				59
Building Solutions Asia Pacific | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				16
Global Products | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				32
Continuing Operations | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				347
Power Solutions | Transfer To Held for Sale [Member] | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Settled without Cash	(3)
Power Solutions | Transfer To Held for Sale [Member] | Employee Severance | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Settled without Cash	(3)
Power Solutions | Transfer To Held for Sale [Member] | Fixed Asset Impairment | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Settled without Cash	0
Power Solutions | Transfer To Held for Sale [Member] | Other Restructuring | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Settled without Cash	0
Power Solutions | Transfer To Held for Sale [Member] | Currency Translation | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Settled without Cash	$ 0
Power Solutions | Discontinued Operations | 2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs				$ 20