v3.26.1
Investment Securities Schedule of Amortized Cost and Fair Values of Investment Securities (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Schedule of Investments [Line Items]    
Amortized Cost $ 3,800,886  
Gross Unrealized Gains 8,233  
Gross Unrealized Losses (248,069)  
Estimated Fair Value 3,561,050 $ 3,407,859
Amortized Cost, Held to Maturity 1,561,709 1,425,885
Gross Unrealized Gains, Held to Maturity 2,936 4,978
Gross Unrealized Losses, Held to Maturity (170,907) (163,285)
Debt Securities, Held-to-Maturity, Fair Value 1,393,738 1,267,578
US States and Political Subdivisions Debt Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 931,962 951,764
Gross Unrealized Gains 224 326
Gross Unrealized Losses (116,231) (125,397)
Estimated Fair Value 815,955 826,693
Corporate Debt Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 210,070 219,699
Gross Unrealized Gains 1,596 1,302
Gross Unrealized Losses (4,091) (6,080)
Estimated Fair Value 207,575 214,921
Collateralized Mortgage Obligations [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 1,192,896 1,034,548
Gross Unrealized Gains 3,062 12,758
Gross Unrealized Losses (11,639) (7,228)
Estimated Fair Value 1,184,319 1,040,078
Amortized Cost, Held to Maturity 163,019  
Gross Unrealized Gains, Held to Maturity 0  
Gross Unrealized Losses, Held to Maturity (2,840)  
Debt Securities, Held-to-Maturity, Fair Value 160,179  
Mortgage-Backed Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 786,030 781,966
Gross Unrealized Gains 3,351 5,891
Gross Unrealized Losses (23,853) (21,140)
Estimated Fair Value 765,528 766,717
Amortized Cost, Held to Maturity 516,680 573,636
Gross Unrealized Gains, Held to Maturity 2,936 4,978
Gross Unrealized Losses, Held to Maturity (44,721) (44,093)
Debt Securities, Held-to-Maturity, Fair Value 474,895 534,521
Commercial Mortgage Backed Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 679,928 647,375
Gross Unrealized Gains 0 80
Gross Unrealized Losses (92,255) (88,005)
Estimated Fair Value 587,673 559,450
Amortized Cost, Held to Maturity 882,010 852,249
Gross Unrealized Gains, Held to Maturity 0 0
Gross Unrealized Losses, Held to Maturity (123,346) (119,192)
Debt Securities, Held-to-Maturity, Fair Value $ 758,664 733,057
Debt Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost   3,635,352
Gross Unrealized Gains   20,357
Gross Unrealized Losses   (247,850)
Estimated Fair Value   $ 3,407,859