Fair Value (Fair Value Measurements - Nonrecurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	$ 358	$ 400
Finance receivables and loans, net	134,410	135,852
Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	331	375
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	0	0
Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	395	441
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(42)	(43)
Nonmarketable equity investments | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	5	1
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	2	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	10
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(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
Level 1 | Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	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	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
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
Level 2 | Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	3	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	3	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
Level 3 | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale, net	331	375
Level 3 | Assets | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	392	441
Level 3 | Nonmarketable equity investments | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets	2	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	10
Commercial | Nonrecurring fair value measurements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance receivables and loans, net	51	55
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(43)	(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
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
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	51	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	2	6
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	0	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
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
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	2	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	49	49
Lower-of-cost-or-fair-value reserve, valuation reserve, or cumulative adjustments	(43)	(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
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
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	$ 49	$ 49