Basis of Presentation Disaggregated Revenue in Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Other related Revenue	$ 22	$ 33	$ 54	$ 63
Revenues	760	2,337	2,513	4,257
Corporate Interest Expense [Member]
Disaggregation of Revenue [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax	1	1	1	2
Americas [Member]
Disaggregation of Revenue [Line Items]
Revenues	565	1,627	1,822	2,954
EMEA [Member]
Disaggregation of Revenue [Line Items]
Revenues	159	572	516	1,005
Asia and Australasia [Member]
Disaggregation of Revenue [Line Items]
Revenues	36	138	175	298
Avis [Member]
Disaggregation of Revenue [Line Items]
Revenues	402	1,328	1,387	2,428
Budget [Member]
Disaggregation of Revenue [Line Items]
Revenues	267	816	886	1,467
Other Brands [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 91	$ 193	$ 240	$ 362