v3.26.1
Investment Securities - Amortized Cost and Fair Value of Securities Available-for-Sale (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Jun. 30, 2025
Dec. 31, 2024
Schedule of Available-for-sale Securities [Line Items]        
Amortized Cost $ 2,997,415 $ 3,088,820    
Allowance for Credit Losses 0 0 $ (2,195) $ (2,195)
Net Carrying Amount 2,997,415 3,088,820    
Gross Unrealized Gains 5,712 6,493    
Gross Unrealized (Losses) (226,911) (223,382)    
Estimated Fair Value 2,776,216 2,871,931    
U.S. government-sponsored enterprises        
Schedule of Available-for-sale Securities [Line Items]        
Amortized Cost 210,738 246,891    
Allowance for Credit Losses 0 0    
Net Carrying Amount 210,738 246,891    
Gross Unrealized Gains 885 998    
Gross Unrealized (Losses) (7,237) (7,107)    
Estimated Fair Value 204,386 240,782    
U.S. government-sponsored mortgage-backed securities        
Schedule of Available-for-sale Securities [Line Items]        
Amortized Cost 1,302,974 1,345,469    
Allowance for Credit Losses 0 0    
Net Carrying Amount 1,302,974 1,345,469    
Gross Unrealized Gains 1,247 1,478    
Gross Unrealized (Losses) (144,283) (133,999)    
Estimated Fair Value 1,159,938 1,212,948    
Private mortgage-backed securities        
Schedule of Available-for-sale Securities [Line Items]        
Amortized Cost 176,380 152,578    
Allowance for Credit Losses 0 0    
Net Carrying Amount 176,380 152,578    
Gross Unrealized Gains 75 126    
Gross Unrealized (Losses) (8,694) (6,984)    
Estimated Fair Value 167,761 145,720    
Non-government-sponsored asset backed securities        
Schedule of Available-for-sale Securities [Line Items]        
Amortized Cost 97,958 158,446    
Allowance for Credit Losses 0 0    
Net Carrying Amount 97,958 158,446    
Gross Unrealized Gains 59 325    
Gross Unrealized (Losses) (1,136) (927)    
Estimated Fair Value 96,881 157,844    
State and political subdivisions        
Schedule of Available-for-sale Securities [Line Items]        
Amortized Cost 961,342 951,822    
Allowance for Credit Losses 0 0    
Net Carrying Amount 961,342 951,822    
Gross Unrealized Gains 1,448 1,419    
Gross Unrealized (Losses) (57,457) (65,403)    
Estimated Fair Value 905,333 887,838    
Other securities        
Schedule of Available-for-sale Securities [Line Items]        
Amortized Cost 248,023 233,614    
Allowance for Credit Losses 0 0    
Net Carrying Amount 248,023 233,614    
Gross Unrealized Gains 1,998 2,147    
Gross Unrealized (Losses) (8,104) (8,962)    
Estimated Fair Value $ 241,917 $ 226,799