Revenue Revenue - Narrative (Details) - Operating Segments - Automotive - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Vehicles, parts, and accessories
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue Performance Obligation Satisfied In Prior Period			$ 214	$ 48
Services and other revenue (a)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Liability	$ 4,300		4,300		$ 4,200
Contract with Customer, Liability, Revenue Recognized	336	$ 276	678	606
Capitalized Contract Cost, Net	304		304		$ 283
Capitalized Contract Cost, Amortization	$ 19	$ 19	$ 39	$ 39