Revenue Revenue Remaining Performance Obligation, Expected Timing of Satisfaction (Details) - Extended service contracts - Automotive - Operating Segments [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Capitalized Contract Cost, Amortization	$ 19	$ 14	$ 37	$ 29
Contract with Customer, Liability, Revenue Recognized	269	$ 271	$ 567	$ 541
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	600		$ 600
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	1,000		$ 1,000
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	$ 3,900		$ 3,900