Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 2,385	$ 2,509
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	1,345	1,434
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	874	909
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	166	166
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	1,885	1,974
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	342	364
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 158	$ 171