v3.26.1
Fair Value Accounting - Fair Value of Assets and Liabilities (Detail) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS $ 18,701 $ 18,788    
Investment securities - equity 79 79    
Fair value of mortgage servicing rights 1,516 1,494 $ 1,241 $ 1,127
Derivative asset 402 488 253  
Derivative liabilities 36 28 $ 25  
CLO        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 2,966 2,747    
Commercial MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 471 635    
Corporate debt securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 297 297    
Private label residential MBS        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 1,005 1,039    
Residential MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 7,497 7,230    
Tax-exempt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 788 802    
U.S. Treasury securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 5,610 5,970    
Other        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 67 68    
CRA investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 28 27    
Preferred Stock        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 51 52    
Loans HFI        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Cumulative basis adjustment, including carrying value of hedged items increase (decrease) (26) 0    
Fair Value, Recurring        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 18,701 18,788    
Investment securities - equity 79 79    
Loans HFS 3,815 3,364    
Fair value of mortgage servicing rights 1,516 1,494    
Derivative asset 276 207    
Junior subordinated debt 70 71    
Derivative liabilities 139 106    
Fair Value, Recurring | CLO        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 2,966 2,747    
Fair Value, Recurring | Commercial MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 471 635    
Fair Value, Recurring | Corporate debt securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 297 297    
Fair Value, Recurring | Private label residential MBS        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 1,005 1,039    
Fair Value, Recurring | Residential MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 7,497 7,230    
Fair Value, Recurring | Tax-exempt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 788 802    
Fair Value, Recurring | U.S. Treasury securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 5,610 5,970    
Fair Value, Recurring | Other        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 67 68    
Fair Value, Recurring | CRA investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 28 27    
Fair Value, Recurring | Preferred Stock        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 51 52    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 5,638 5,998    
Investment securities - equity 79 79    
Loans HFS 0 0    
Fair value of mortgage servicing rights 0 0    
Derivative asset 0 0    
Junior subordinated debt 0 0    
Derivative liabilities 0 0    
Margin, asset 260 366    
Margin, liability 31 7    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | CLO        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Private label residential MBS        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Tax-exempt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 5,610 5,970    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 28 28    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | CRA investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 28 27    
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Preferred Stock        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 51 52    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2)        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 13,063 12,790    
Investment securities - equity 0 0    
Loans HFS 2,804 2,664    
Fair value of mortgage servicing rights 0 0    
Derivative asset 227 148    
Junior subordinated debt 0 0    
Derivative liabilities 127 105    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | CLO        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 2,966 2,747    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Commercial MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 471 635    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 297 297    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Private label residential MBS        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 1,005 1,039    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Residential MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 7,497 7,230    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Tax-exempt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 788 802    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Treasury securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Other        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 39 40    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | CRA investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 0 0    
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Preferred Stock        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3)        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Investment securities - equity 0 0    
Loans HFS 1,011 700    
Fair value of mortgage servicing rights 1,516 1,494    
Derivative asset 49 59    
Junior subordinated debt 70 71    
Derivative liabilities 12 1    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | CLO        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Commercial MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Private label residential MBS        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Residential MBS issued by GSEs and GNMA        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Tax-exempt        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | U.S. Treasury securities        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Other        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
AFS 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | CRA investments        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity 0 0    
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Preferred Stock        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Investment securities - equity $ 0 $ 0