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Investment Securities - Additional Information (Detail)
3 Months Ended 9 Months Ended
Sep. 30, 2022
USD ($)
Security
Sep. 30, 2021
USD ($)
Sep. 30, 2022
USD ($)
Security
Sep. 30, 2021
USD ($)
Dec. 31, 2021
USD ($)
Investment Holdings [Line Items]          
Gross realized gains(loss) on sale of investment securities $ 0 $ 0 $ 0 $ 0  
Gains (losses) on equity securities $ (1,108,000) 291,000 $ (1,913,000) $ (22,646,000)  
Number of debt securities with aggregate gross unrealized losses | Security 4,330   4,330    
Unrealized losses on individual debt securities     $ 1,800,000,000    
Cost method equity securities $ 640,000,000   640,000,000    
Investment securities pledged to secure debt carrying value 10,300,000,000   10,300,000,000   $ 5,100,000,000
Carrying value of investment securities pledged related to repurchase transactions 581,000,000   581,000,000   96,000,000
Maximum [Member]          
Investment Holdings [Line Items]          
Gains (losses) on equity securities   $ 1,000,000      
Available-for-Sale Securities [Member]          
Investment Holdings [Line Items]          
Allowance for credit losses $ 0   $ 0   $ 0