Revenue Revenue Remaining Performance Obligation, Expected Timing of Satisfaction (Details) - Extended service contracts - Automotive - Operating Segments [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Capitalized Contract Cost, Amortization	$ 18	$ 17	$ 55	$ 46
Contract with Customer, Liability, Revenue Recognized	262	$ 256	$ 829	$ 797
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation expected timing of satisfaction period			1 year
Revenue, Remaining Performance Obligation	300		$ 300
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation expected timing of satisfaction period			1 year
Revenue, Remaining Performance Obligation	1,100		$ 1,100
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation expected timing of satisfaction period			8 years
Revenue, Remaining Performance Obligation	$ 4,000		$ 4,000