Fair Value (Fair Value Measurements - Nonrecurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	$ 289	$ 654
Finance receivables and loans, net	136,423	132,037
Assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	417	700
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(95)	(86)
Loans held-for-sale, net | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	260	641
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	0	0
Nonmarketable equity investments | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets		12
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments		3
Repossessed and foreclosed assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	6	5
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(1)	0
Level 1 | Assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 1 | Loans held-for-sale, net | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0	0
Level 1 | Nonmarketable equity investments | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets		0
Level 1 | Repossessed and foreclosed assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0	0
Level 2 | Assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Level 2 | Loans held-for-sale, net | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	0	0
Level 2 | Nonmarketable equity investments | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets		0
Level 2 | Repossessed and foreclosed assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	0	0
Level 3 | Assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	417	700
Level 3 | Loans held-for-sale, net | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	260	641
Level 3 | Nonmarketable equity investments | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets		12
Level 3 | Repossessed and foreclosed assets | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	6	5
Commercial | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	151	42
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(94)	(89)
Commercial | Level 1 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0
Commercial | Level 2 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0
Commercial | Level 3 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	151	42
Automotive | Commercial | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	73	3
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(17)	0
Automotive | Commercial | Level 1 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0
Automotive | Commercial | Level 2 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0
Automotive | Commercial | Level 3 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	73	3
Other | Commercial | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	78	39
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(77)	(89)
Other | Commercial | Level 1 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0
Other | Commercial | Level 2 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	0	0
Other | Commercial | Level 3 | Fair Value, measurements, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	$ 78	$ 39