Leases Lessor (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 1,504	$ 2,713	$ 3,963	$ 6,907
Americas [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	1,099	1,856	2,896	4,792
EMEA [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	350	717	843	1,684
Asia and Australasia [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	55	140	224	431
Avis [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	824	1,559	2,181	3,953
Budget [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	532	935	1,401	2,379
Other Brands [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 148	$ 219	$ 381	$ 575