Segment Information (Summary of Segments Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Revenues	$ 3,480	$ 3,564	$ 9,079	$ 9,244
Adjusted EBITDA	503	907	729	2,179
Reconciliation of Adjusted EBITDA to Income before income taxes:
Non-vehicle related depreciation and amortization	58	55	177	163
Interest expense related to corporate debt, net:
Interest expense	95	80	266	221
Early extinguishment of debt	0	1	1	1
Restructuring and other related charges	6	2	23	7
Transaction-related costs, net	0	3	2	3
Other (income) expense, net	3	1	6	3
Reported within operating expenses:
Legal matters, net			7	5
Income before income taxes	329	757	214	1,752
Operating Expense | Cloud Computing Costs
Reported within operating expenses:
Cloud computing costs	12	8	33	24
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Adjusted EBITDA	(20)	(29)	(57)	(80)
Americas | Geographical
Segment Reporting Information [Line Items]
Revenues	2,640	2,736	6,994	7,180
Adjusted EBITDA	384	740	614	1,887
International | Geographical
Segment Reporting Information [Line Items]
Revenues	840	828	2,085	2,064
Adjusted EBITDA	$ 139	$ 196	$ 172	$ 372