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Investment Securities - Additional Information (Details)
 3 Months Ended 9 Months Ended
Sep. 30, 2025
USD ($)
security
Sep. 30, 2024
USD ($)
Sep. 30, 2025
USD ($)
security
Sep. 30, 2024
USD ($)
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Schedule of Available-for-sale Securities [Line Items]            
Carrying value of investment securities $ 2,660,000,000   $ 2,660,000,000   $ 2,610,000,000  
Investment securities pledged as collateral 146,000,000.0   146,000,000.0   162,400,000  
Available for sale securities sold 0 $ 0 0 $ 0    
Allowance for credit losses 0 2,195,000 0 2,195,000 2,195,000 $ 2,525,000
Allowance for credit losses 2,005,000 $ 2,005,000 2,005,000 $ 2,005,000 2,005,000 $ 2,005,000
Debt securities available for sale unrealized loss position (245,006,000)   (245,006,000)   (338,604,000)  
Fair value of unrealized losses $ 243,930,000   $ 243,930,000   334,860,000  
Percentage of Company's investment portfolio     43.50%      
Maturity description of investment portfolio     five years or less      
Number of investment securities available for sale | security 1,494   1,494      
Number of investment in debt securities available-for-sale unrealized loss position | security 1,206   1,206      
Number of investment securities held to maturity | security 514   514      
Number of investments in debt securities held-to-maturity unrealized loss position | security 494   494      
Unrealized losses $ (107,525,000)   $ (107,525,000)   (132,303,000)  
U.S. government-sponsored enterprises            
Schedule of Available-for-sale Securities [Line Items]            
Allowance for credit losses 0   0   0  
Allowance for credit losses 0   0   0  
Debt securities available for sale unrealized loss position (8,394,000)   (8,394,000)   (14,072,000)  
Fair value of unrealized losses $ 8,330,000   $ 8,330,000   13,746,000  
Number of investment in debt securities available-for-sale unrealized loss position | security 61   61      
Number of investments in debt securities held-to-maturity unrealized loss position | security 5   5      
Unrealized losses $ (1,523,000)   $ (1,523,000)   (3,021,000)  
U.S. government-sponsored mortgage-backed securities            
Schedule of Available-for-sale Securities [Line Items]            
Allowance for credit losses 0   0   0  
Allowance for credit losses 0   0   0  
Debt securities available for sale unrealized loss position (138,541,000)   (138,541,000)   (203,539,000)  
Fair value of unrealized losses $ 138,519,000   $ 138,519,000   202,451,000  
Number of investment in debt securities available-for-sale unrealized loss position | security 616   616      
Number of investments in debt securities held-to-maturity unrealized loss position | security 14   14      
Unrealized losses $ (3,366,000)   $ (3,366,000)   (6,695,000)  
Private mortgage-backed securities            
Schedule of Available-for-sale Securities [Line Items]            
Allowance for credit losses 0   0   0  
Debt securities available for sale unrealized loss position (7,417,000)   (7,417,000)   (13,249,000)  
Fair value of unrealized losses $ 7,417,000   $ 7,417,000   13,120,000  
Number of investment in debt securities available-for-sale unrealized loss position | security 29   29      
Non-government-sponsored asset backed securities            
Schedule of Available-for-sale Securities [Line Items]            
Allowance for credit losses $ 0   $ 0    
Debt securities available for sale unrealized loss position (1,067,000)   (1,067,000)   (3,434,000)  
Fair value of unrealized losses $ 1,066,000   $ 1,066,000   3,374,000  
Number of investment in debt securities available-for-sale unrealized loss position | security 15   15      
State and political subdivisions            
Schedule of Available-for-sale Securities [Line Items]            
Allowance for credit losses $ 0   $ 0   0  
Allowance for credit losses 2,005,000   2,005,000   2,005,000  
Debt securities available for sale unrealized loss position (78,219,000)   (78,219,000)   (86,029,000)  
Fair value of unrealized losses $ 77,308,000   $ 77,308,000   84,799,000  
Number of investment in debt securities available-for-sale unrealized loss position | security 426   426      
Number of investments in debt securities held-to-maturity unrealized loss position | security 475   475      
Unrealized losses $ (102,636,000)   $ (102,636,000)   (122,587,000)  
Other securities            
Schedule of Available-for-sale Securities [Line Items]            
Allowance for credit losses 0   0   2,195,000  
Debt securities available for sale unrealized loss position (11,368,000)   (11,368,000)   (18,281,000)  
Fair value of unrealized losses $ 11,290,000   $ 11,290,000   $ 17,370,000  
Number of investment in debt securities available-for-sale unrealized loss position | security 59   59