Unrecognized Tax Benefits Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Unrecognized tax benefits, non-current income taxes payable	$ 24	$ 57
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	29	27
Unrecognized Tax Benefits	57	$ 54	$ 61	$ 63
Non Avis Budget Car Rental Tax Contingencies
Income Taxes [Line Items]
Unrecognized Tax Benefits	$ 13