v3.25.2
Fair Value Accounting - Fair Value of Assets and Liabilities (Detail) - USD ($)
$ in Millions
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS $ 16,898.0   $ 13,468.0      
Investment securities - Trading, at fair value 53.0   0.0      
Investment securities - equity 122.0   117.0      
Fair value of mortgage servicing rights 1,044.0 $ 1,241.0 1,127.0 $ 1,145.0 $ 1,178.0 $ 1,124.0
Derivative asset 389.0   253.0 244.0    
Junior subordinated debt 69.0   65.0      
Derivative liabilities 28.0   27.0 $ 28.0    
Residential MBS issued by GSEs and GNMA            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 6,666.0   5,831.0      
Investment securities - Trading, at fair value 53.0          
U.S. Treasury securities            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 5,504.0   4,383.0      
Private label residential MBS            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 990.0   947.0      
CLO            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 1,901.0   570.0      
Tax-exempt            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 796.0   845.0      
Commercial MBS issued by GSEs and GNMA            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 599.0   437.0      
Corporate debt securities            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 374.0   386.0      
Other            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 68.0   69.0      
Preferred Stock            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 63.0   91.0      
Common Stock            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 32.0          
CRA investments            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 27.0   26.0      
Fair Value, Recurring            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 16,898.0   13,468.0      
Investment securities - Trading, at fair value 53.0          
Investment securities - equity 122.0   117.0      
Loans HFS 2,980.0   2,244.0      
Fair value of mortgage servicing rights 1,044.0   1,127.0      
Derivative asset 176.0   233.0      
Derivative liabilities 203.0   76.0      
Fair Value, Recurring | Residential MBS issued by GSEs and GNMA            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 6,666.0   5,831.0      
Investment securities - Trading, at fair value 53.0          
Fair Value, Recurring | U.S. Treasury securities            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 5,504.0   4,383.0      
Fair Value, Recurring | Private label residential MBS            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 990.0   947.0      
Fair Value, Recurring | CLO            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 1,901.0   570.0      
Fair Value, Recurring | Tax-exempt            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 796.0   845.0      
Fair Value, Recurring | Commercial MBS issued by GSEs and GNMA            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 599.0   437.0      
Fair Value, Recurring | Corporate debt securities            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 374.0   386.0      
Fair Value, Recurring | Other            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 68.0   69.0      
Fair Value, Recurring | Preferred Stock            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 63.0   91.0      
Fair Value, Recurring | Common Stock            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 32.0          
Fair Value, Recurring | CRA investments            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 27.0   26.0      
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 5,532.0   4,385.0      
Investment securities - Trading, at fair value 0.0          
Investment securities - equity 122.0   117.0      
Loans HFS 0.0   0.0      
Fair value of mortgage servicing rights 0.0   0.0      
Derivative asset 0.0   0.0      
Junior subordinated debt 0.0   0.0      
Derivative liabilities 0.0   0.0      
Margin, asset 347.0   72.0      
Margin, liability (41.0)   3.0      
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   0.0      
Investment securities - Trading, at fair value 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 5,504.0   4,383.0      
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   0.0      
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   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   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   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   0.0      
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 28.0   2.0      
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 63.0   91.0      
Fair Value, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 32.0          
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 27.0   26.0      
Fair Value, Recurring | Significant Other Observable Inputs (Level 2)            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 11,366.0   9,083.0      
Investment securities - Trading, at fair value 53.0          
Investment securities - equity 0.0   0.0      
Loans HFS 2,896.0   2,240.0      
Fair value of mortgage servicing rights 0.0   0.0      
Derivative asset 119.0   198.0      
Junior subordinated debt 0.0   0.0      
Derivative liabilities 203.0   69.0      
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 6,666.0   5,831.0      
Investment securities - Trading, at fair value 53.0          
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   0.0      
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 990.0   947.0      
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | CLO            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 1,901.0   570.0      
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 796.0   845.0      
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 599.0   437.0      
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 374.0   386.0      
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Other            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
AFS 40.0   67.0      
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   0.0      
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Common Stock            
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) | CRA investments            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity 0.0   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   0.0      
Investment securities - Trading, at fair value 0.0          
Investment securities - equity 0.0   0.0      
Loans HFS 84.0   4.0      
Fair value of mortgage servicing rights 1,044.0   1,127.0      
Derivative asset 57.0   35.0      
Junior subordinated debt 69.0   65.0      
Derivative liabilities 0.0   7.0      
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   0.0      
Investment securities - Trading, at fair value 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   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   0.0      
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   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   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   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   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   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   0.0      
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Common 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) | CRA investments            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Investment securities - equity $ 0.0   $ 0.0