Fair Value - Schedule of Fair Value Measurements - Nonrecurring Basis (Details) - USD ($) $ in Millions		12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	$ 160	$ 160	$ 400
Finance receivables and loans, net	132,316	132,316	135,852
Goodwill impairment		118	149	$ 0
Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	143	143	375
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	0	0	0
Goodwill impairment	118
Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	552	552	441
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(184)	(184)	(43)
Goodwill | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	362	362
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(118)	(118)
Nonmarketable equity investments | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets			1
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments			1
Repossessed and foreclosed assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	8	8	10
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(1)	(1)	(1)
Level 1 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0	0	0
Level 1 | Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0	0
Level 1 | Goodwill | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0	0
Level 1 | Nonmarketable equity investments | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets			0
Level 1 | Repossessed and foreclosed assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0	0	0
Level 2 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0	0	0
Level 2 | Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0	0
Level 2 | Goodwill | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0	0
Level 2 | Nonmarketable equity investments | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets			0
Level 2 | Repossessed and foreclosed assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0	0	0
Level 3 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	143	143	375
Level 3 | Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	552	552	441
Level 3 | Goodwill | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	362	362
Level 3 | Nonmarketable equity investments | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets			1
Level 3 | Repossessed and foreclosed assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	8	8	10
Commercial | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	39	39	55
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(65)	(65)	(43)
Commercial | Level 1 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0	0
Commercial | Level 2 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0	0
Commercial | Level 3 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	39	39	55
Automotive | Commercial | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	13	13	6
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(2)	(2)	0
Automotive | Commercial | Level 1 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0	0
Automotive | Commercial | Level 2 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0	0
Automotive | Commercial | Level 3 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	13	13	6
Other | Commercial | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	26	26	49
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(63)	(63)	(43)
Other | Commercial | Level 1 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0	0
Other | Commercial | Level 2 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0	0
Other | Commercial | Level 3 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	$ 26	$ 26	$ 49