v3.26.1
Securities - Additional Information (Detail) - USD ($)
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Dec. 31, 2022
Schedule of Trading Securities and Other Trading Assets [Line Items]            
Proceeds from sales of securities available for sale $ 5,375,000 $ 4,931,000 $ 57,146,000 $ 616,354,000    
Fair Value 13,488,159,000   13,488,159,000   $ 13,709,141,000  
Gross realized gains from securities 26,000 33,000 429,000 423,000    
Accrued interest on securities available for sale 80,100,000   80,100,000   82,900,000  
ACL related to AFS Securities 0   0   0  
Sales of securities held to maturity 0 $ 0 0 0    
Amortized cost of available for sale securities transferred to held to maturity           $ 4,100,000,000
Fair value of available for sale securities transferred to held to maturity           $ 3,800,000,000
Gain (loss) on transfer of securities     0      
Unamortized unrealized loss 124,900,000   124,900,000   139,200,000  
Accrued interest on securities held to maturity 30,200,000   30,200,000   28,000,000  
Unrealized gain (loss) on trading securities     13,000 $ 48,000    
Securities sold not yet purchased 14,000,000   14,000,000   4,100,000  
Securities held to maturity with an acquired fair value 5,239,447,000   5,239,447,000   5,250,465,000  
Other securities 693,502,000   693,502,000   676,300,000  
Collateral Pledged [Member] | U.S. Government and Other Public Deposit [Member]            
Schedule of Trading Securities and Other Trading Assets [Line Items]            
Pledged securities for deposits $ 13,200,000,000   $ 13,200,000,000   $ 13,400,000,000