Goodwill and Intangible Assets, Net - Summary of Fair Value of Acquired Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Intangible assets:
Total	$ 5	$ 6
Goodwill	9	9
Car360
Intangible assets:
Intangible assets, acquired cost	10	10
Less: accumulated amortization	(5)	(4)
Total	5	6
Goodwill	$ 9	9
Car360 | Developed technology
Intangible assets:
Useful Life	7 years
Intangible assets, acquired cost	$ 9	9
Car360 | Non-compete agreements
Intangible assets:
Useful Life	5 years
Intangible assets, acquired cost	$ 1	$ 1