Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 3,511	$ 3,496	$ 9,105	$ 9,096
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	2,011	1,926	5,120	4,915
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	1,298	1,356	3,430	3,598
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	202	214	555	583
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	2,715	2,682	7,120	7,216
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	646	654	1,518	1,468
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 150	$ 160	$ 467	$ 412