Leases Lessor (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 738	$ 2,304	$ 2,459	$ 4,194
Americas [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	552	1,617	1,796	2,936
EMEA [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	151	553	493	967
Asia and Australasia [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	35	134	170	291
Avis [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	389	1,311	1,357	2,394
Budget [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	261	804	869	1,444
Other Brands [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 88	$ 189	$ 233	$ 356