Leases (Lessor) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 2,398	$ 1,332
Avis
Lessor, Lease, Description [Line Items]
Total lease revenues	1,261	690
Budget
Lessor, Lease, Description [Line Items]
Total lease revenues	972	516
Other
Lessor, Lease, Description [Line Items]
Total lease revenues	165	126
Americas
Lessor, Lease, Description [Line Items]
Total lease revenues	1,985	1,054
Europe, Middle East and Africa
Lessor, Lease, Description [Line Items]
Total lease revenues	309	192
Asia and Australasia
Lessor, Lease, Description [Line Items]
Total lease revenues	$ 104	$ 86