Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 3,202	$ 2,352	$ 5,600	$ 3,684
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	1,728	1,201	2,989	1,891
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	1,270	975	2,242	1,491
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	204	176	369	302
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	2,549	1,972	4,534	3,026
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	505	268	814	460
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 148	$ 112	$ 252	$ 198