v3.25.1
Fair Value Measurements - Assets and Liabilities Recorded as Fair Value on Nonrecurring Basis (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total Gains (Losses) $ (51) $ 1  
Consumer loans      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total Gains (Losses) 1 1  
Commercial loans held for sale      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total Gains (Losses) 0 2  
Commercial Loans      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total Gains (Losses) (52) $ (2)  
Fair Value, Nonrecurring      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 570   $ 450
Fair Value, Nonrecurring | Level 1      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 0   0
Fair Value, Nonrecurring | Level 2      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 127   100
Fair Value, Nonrecurring | Level 3      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 443   350
Fair Value, Nonrecurring | Consumer loans      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 98   100
Fair Value, Nonrecurring | Consumer loans | Level 1      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 0   0
Fair Value, Nonrecurring | Consumer loans | Level 2      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 98   100
Fair Value, Nonrecurring | Consumer loans | Level 3      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 0   0
Fair Value, Nonrecurring | Commercial loans held for sale      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 29   0
Fair Value, Nonrecurring | Commercial loans held for sale | Level 1      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 0   0
Fair Value, Nonrecurring | Commercial loans held for sale | Level 2      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 29   0
Fair Value, Nonrecurring | Commercial loans held for sale | Level 3      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 0   0
Fair Value, Nonrecurring | Commercial Loans      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 443   350
Fair Value, Nonrecurring | Commercial Loans | Level 1      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 0   0
Fair Value, Nonrecurring | Commercial Loans | Level 2      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis 0   0
Fair Value, Nonrecurring | Commercial Loans | Level 3      
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]      
Total assets at fair value on a non-recurring basis $ 443   $ 350