v3.26.1
Investment Securities (Narrative) (Details)
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Security
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Security
Jun. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Security
Schedule Of Investments [Line Items]          
Securities pledged as collateral $ 948,600,000   $ 948,600,000   $ 860,300,000
Proceeds from Sale of Debt Securities, Available-for-Sale $ 0 $ 64,955,000 $ 18,379,000 $ 64,955,000  
Number of security positions, unrealized loss position | Security 75   75   54
Number of security positions, unrealized loss position for more than 12 months | Security 40   40    
Securities, 12 months or longer, Fair Value $ 272,100,000   $ 272,100,000    
Securities, 12 months or longer, Unrealized Losses $ 49,200,000   $ 49,200,000    
Number of security positions, unrealized loss position for less than 12 months | Security 35   35    
Securities, Less than 12 months, Fair Value $ 292,600,000   $ 292,600,000    
Securities, Less than 12 months, Unrealized Losses 3,200,000   3,200,000    
Available for sale securities, allowance for credit loss 0   0   $ 0
Securities held to maturity, Amortized Cost 79,300,000   79,300,000   84,710,000
Internally rated held-to-maturity securities $ 3,100,000   $ 3,100,000   $ 4,100,000
Investment, Type [Extensible Enumeration] Municipal Bonds [Member]   Municipal Bonds [Member]   Municipal Bonds [Member]
Investment securities, past due $ 4,752,965,000   $ 4,752,965,000   $ 4,657,866,000
Total Past Due [Member]          
Schedule Of Investments [Line Items]          
Investment securities, past due 29,531,000   29,531,000   28,477,000
Municipal Bonds [Member]          
Schedule Of Investments [Line Items]          
Securities held to maturity, Amortized Cost 27,200,000   27,200,000   28,800,000
Available for Sale Securities [Member]          
Schedule Of Investments [Line Items]          
Accrued interest receivable 3,600,000   3,600,000   3,500,000
Held To Maturity Investment Securities [Member]          
Schedule Of Investments [Line Items]          
Accrued interest receivable 308,000   308,000   348,000
Held To Maturity Investment Securities [Member] | Total Past Due [Member]          
Schedule Of Investments [Line Items]          
Investment securities, past due 0   0   $ 0
Held To Maturity Investment Securities [Member] | Maximum [Member]          
Schedule Of Investments [Line Items]          
Provision for credit loss $ 1,000 $ 1,000 $ 1,000 $ 1,000