Leases Lessor (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 1,721	$ 1,890
Americas [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	1,244	1,319
EMEA [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	342	414
Asia and Australasia [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	135	157
Avis [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	968	1,083
Budget [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	608	640
Other Brands [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 145	$ 167