Unrecognized Tax Benefits Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Unrecognized tax benefits, non-current income taxes payable	$ 46	$ 40
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	26	29
Unrecognized Tax Benefits	63	59	$ 56	$ 63
Non Avis Budget Car Rental Tax Contingencies
Income Taxes [Line Items]
Unrecognized Tax Benefits	$ 13	$ 15