Summary of Significant Accounting Policies - Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 11,994	$ 9,313	$ 5,402
Avis
Disaggregation of Revenue [Line Items]
Revenues	6,519	4,894	2,961
Budget
Disaggregation of Revenue [Line Items]
Revenues	4,701	3,715	1,908
Other
Disaggregation of Revenue [Line Items]
Revenues	774	704	533
Americas
Disaggregation of Revenue [Line Items]
Revenues	9,474	7,557	3,965
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	1,927	1,400	1,127
Asia and Australasia
Disaggregation of Revenue [Line Items]
Revenues	$ 593	$ 356	$ 310