Basis of Presentation (Disaggregated Revenue in Basis of Presentation) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 2,432	$ 1,372
Avis
Disaggregation of Revenue [Line Items]
Revenues	1,281	717
Budget
Disaggregation of Revenue [Line Items]
Revenues	982	524
Other
Disaggregation of Revenue [Line Items]
Revenues	169	131
Americas
Disaggregation of Revenue [Line Items]
Revenues	2,000	1,080
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	324	203
Asia and Australasia
Disaggregation of Revenue [Line Items]
Revenues	$ 108	$ 89