Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 2,509	$ 2,513
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	1,434	1,388
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	909	964
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	166	161
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	1,974	1,995
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	364	349
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 171	$ 169