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Securities - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Dec. 31, 2021
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Proceeds from sales of securities available for sale $ 0 $ 129,128,000  
Gross realized gains from securities 0 2,720,000  
Gross realized losses from securities 0 0  
Accrued interest on securities available for sale 27,100,000   $ 45,800,000
Sales of securities held to maturity 0 0  
Amortized cost of available for sale securities transferred to held to maturity 3,000,000,000.0    
Fair value of available for sale securities transferred to held to maturity 2,900,000,000    
Gain (loss) on transfer of securities 0    
Unamortized unrealized loss 155,700,000    
Accrued interest on securities held to maturity 17,000,000.0   5,300,000
Unrealized gain (loss) on trading securities (280,000) $ (40,000)  
Securities sold not yet purchased 1,600,000   3,200,000
Collateral Pledged Against Deposits [Member] | U.S. Government and Other Public Deposit [Member]      
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Pledged securities for deposits 9,300,000,000   10,200,000,000
Collateral Pledged Against Deposits [Member] | Federal Reserve Discount Window [Member]      
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Pledged securities for deposits $ 148,700,000   $ 171,200,000