Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 2,994	$ 3,081	$ 5,503	$ 5,594
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	1,710	1,721	3,144	3,109
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	1,105	1,168	2,014	2,132
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	179	192	345	353
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	2,330	2,410	4,304	4,405
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	524	523	888	872
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 140	$ 148	$ 311	$ 317