Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 3,392	$ 3,511	$ 8,895	$ 9,105
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	1,953	2,011	5,097	5,120
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	1,247	1,298	3,261	3,430
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	192	202	537	555
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	2,587	2,715	6,891	7,120
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	660	646	1,548	1,518
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 145	$ 150	$ 456	$ 467