Segment Information (Summary of Segments Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Revenues	$ 3,048	$ 3,123	$ 5,599	$ 5,680
Adjusted EBITDA	214	737	226	1,272
Reconciliation of Adjusted EBITDA to Income (loss) before income taxes:
Non-vehicle related depreciation and amortization	58	52	119	108
Interest expense related to corporate debt, net:
Interest expense	88	68	171	141
Early extinguishment of debt	1	0	1	0
Restructuring and other related charges	14	1	17	5
Transaction-related costs, net	1	0	2	0
Other (income) expense, net	2	4	3	2
Reported within operating expenses:
Legal matters, net	12	5	7	5
Income (loss) before income taxes	27	598	(115)	995
Operating Expense | Cloud Computing Costs
Reported within operating expenses:
Cloud computing costs	11	9	21	16
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Adjusted EBITDA	(20)	(20)	(37)	(51)
Americas | Geographical
Segment Reporting Information [Line Items]
Revenues	2,361	2,428	4,354	4,444
Adjusted EBITDA	186	631	230	1,147
International | Geographical
Segment Reporting Information [Line Items]
Revenues	687	695	1,245	1,236
Adjusted EBITDA	$ 48	$ 126	$ 33	$ 176