Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 3,081	$ 3,202	$ 5,594	$ 5,600
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	1,721	1,728	3,109	2,989
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	1,168	1,270	2,132	2,242
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	192	204	353	369
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	2,410	2,549	4,405	4,534
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	523	505	872	814
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 148	$ 148	$ 317	$ 252