Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2025
Loss Contingencies [Line Items]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets (Note 2; Note 9)	Other assets (Note 2; Note 9)
Operating lease right-of-use asset	$ 113	$ 90
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities	Other liabilities
Operating lease liabilities	$ 130	$ 105
Operating lease right-of-use asset obtained in exchange for lease obligations	39	17
Rent expense	$ 38	$ 39	$ 37
Weighted-average discount rate (as a percent)	5.40%	4.70%
Weighted average remaining lease term (in years)	7 years 1 month 6 days	4 years 8 months 12 days
Payments for operating leases	$ 50	$ 46	$ 49
Amount of lease agreements not yet commenced	0
Indirect tax contingency	161
Electric Vehicles
Loss Contingencies [Line Items]
Other commitment				$ 2,100
Purchase commitment remaining	$ 293
Texas | Accounts Receivable | Geographic Concentration Risk | Retail Finance Receivables
Loss Contingencies [Line Items]
Concentration risk (as a percent)	14.80%