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Investment Securities - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2024
USD ($)
security
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Dec. 31, 2021
USD ($)
Schedule of Available-for-sale Securities [Line Items]        
Carrying value of investment securities $ 2,610,000,000 $ 3,570,000,000    
Investment securities pledged as collateral 162,400,000 142,100,000    
Available for sale securities sold 0 0 $ 67,300,000  
Provision for credit loss (330,000) 1,683,000 0  
Investment securities, provision for credit losses 2,195,000 2,525,000 842,000 $ 842,000
Allowance for credit loss, held-to-maturity 2,005,000 2,005,000 2,005,000 $ 0
Provision for credit losses 0 0 $ 2,005,000  
Fair value of unrealized losses $ 334,860,000 $ 333,485,000    
Percentage of Company's investment portfolio 38.90% 30.40%    
Number of investment securities available for sale | security 1,535      
Number of investment in debt securities unrealized loss position | security 1,306      
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss $ (338,604,000) $ (336,279,000)    
Number of investment securities held to maturity | security 512      
Number of investments in debt securities held-to-maturity unrealized loss position | security 507      
Unrealized losses $ (132,303,000) (112,063,000)    
U.S. government-sponsored enterprises        
Schedule of Available-for-sale Securities [Line Items]        
Investment securities, provision for credit losses 0 0    
Allowance for credit loss, held-to-maturity 0 0    
Fair value of unrealized losses $ 13,746,000 17,091,000    
Number of investment in debt securities unrealized loss position | security 65      
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss $ (14,072,000) (17,093,000)    
Number of investments in debt securities held-to-maturity unrealized loss position | security 5      
Unrealized losses $ (3,021,000) (2,607,000)    
U.S. government-sponsored mortgage-backed securities        
Schedule of Available-for-sale Securities [Line Items]        
Investment securities, provision for credit losses 0 0    
Allowance for credit loss, held-to-maturity 0 0    
Fair value of unrealized losses $ 202,451,000 189,391,000    
Number of investment in debt securities unrealized loss position | security 650      
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss $ (203,539,000) (191,557,000)    
Number of investments in debt securities held-to-maturity unrealized loss position | security 20      
Unrealized losses $ (6,695,000) (4,362,000)    
Private mortgage-backed securities        
Schedule of Available-for-sale Securities [Line Items]        
Investment securities, provision for credit losses 0 0    
Fair value of unrealized losses $ 13,120,000 15,891,000    
Number of investment in debt securities unrealized loss position | security 32      
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss $ (13,249,000) (16,117,000)    
Non-government-sponsored asset backed securities        
Schedule of Available-for-sale Securities [Line Items]        
Investment securities, provision for credit losses 0 0    
Fair value of unrealized losses $ 3,374,000 7,551,000    
Number of investment in debt securities unrealized loss position | security 23      
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss $ (3,434,000) (7,551,000)    
State and political subdivisions        
Schedule of Available-for-sale Securities [Line Items]        
Investment securities, provision for credit losses 0 0    
Allowance for credit loss, held-to-maturity 2,005,000 2,005,000    
Fair value of unrealized losses $ 84,799,000 75,531,000    
Number of investment in debt securities unrealized loss position | security 474      
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss $ (86,029,000) (75,931,000)    
Number of investments in debt securities held-to-maturity unrealized loss position | security 482      
Unrealized losses $ (122,587,000) (105,094,000)    
Other securities        
Schedule of Available-for-sale Securities [Line Items]        
Investment securities, provision for credit losses 2,195,000 2,525,000    
Fair value of unrealized losses $ 17,370,000 28,030,000    
Number of investment in debt securities unrealized loss position | security 62      
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss $ (18,281,000) $ (28,030,000)