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