Acquisitions - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 1,137	$ 1,101	$ 1,092
2019 Avis and Budget Licensees [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	55
Business Acquisition Purchase Price Allocation Vehicles, Net	27
Payments to Acquire Businesses, Gross	74
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		3 years
Goodwill	21
2019 Avis and Budget Licensees [Member] | Other Intangible Assets [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired	7
2019 Avis and Budget Licensees [Member] | Licensing Agreements [Member]
Business Acquisition [Line Items]
Finite-lived Intangible Assets Acquired	$ 24