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Fair Value Measurements - Additional Information (Detail) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2024 USD ($) | Mar. 31, 2024 USD ($) | Sep. 30, 2023 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($) | Dec. 31, 2023 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Weighted-average discount rates for fair value estimations |  |  |  | 37.00% |  |
Historical recovery rate of collateral values of consumer installment loans |  |  |  | 43.00% |  |
Minimum |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Discount rates for fair value estimations |  |  |  | 10.00% |  |
Maximum |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Discount rates for fair value estimations |  |  |  | 90.00% |  |
Level 3 |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Change in fair value of nonrecurring fair value measured loans for charge-offs and impairment reserves | $ 81,000,000 |  | $ 116,000,000 | $ 204,000,000 | $ 269,000,000 |
Level 3 | Measurement Input, Commitment Expiration |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Held-for-sale measurement input (as a percent) | 0.06 |  |  | 0.06 |  | 0.05
Level 3 | Residential Mortgage Loans |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Capitalized servicing rights, valuation allowance |  | $ 0 |  | $ 0 | 0 |
Nonrecurring |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Loans measured at fair value on nonrecurring basis | $ 805,000,000 |  | 804,000,000 | 805,000,000 | 804,000,000 | $ 923,000,000
Nonrecurring | Level 2 |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Loans measured at fair value on nonrecurring basis | 159,000,000 |  | 316,000,000 | 159,000,000 | 316,000,000 | 234,000,000
Nonrecurring | Level 3 |  |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |  |
Loans measured at fair value on nonrecurring basis | $ 646,000,000 |  | $ 488,000,000 | $ 646,000,000 | $ 488,000,000 | $ 689,000,000

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