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Investment Securities Schedule of Amortized Cost and Fair Values of Investment Securities (Details) - USD ($)
$ in Thousands
Mar. 31, 2023
Dec. 31, 2022
Schedule of Investments [Line Items]    
Amortized Cost $ 2,945,913  
Gross Unrealized Gains 1,000  
Gross Unrealized Losses (304,524)  
Estimated Fair Value 2,642,389 $ 2,646,767
Amortized Cost, Held to Maturity 1,307,712 1,321,256
Gross Unrealized Gains, Held to Maturity 0 0
Gross Unrealized Losses, Held to Maturity (182,685) (196,207)
Debt Securities, Held-to-Maturity, Fair Value 1,125,027 1,125,049
US Government Debt Securities    
Schedule of Investments [Line Items]    
Amortized Cost 225,844 226,140
Gross Unrealized Gains 0 0
Gross Unrealized Losses (5,791) (7,655)
Estimated Fair Value 220,053 218,485
US Government Agencies Debt Securities    
Schedule of Investments [Line Items]    
Amortized Cost 1,047 1,050
Gross Unrealized Gains 0 0
Gross Unrealized Losses (30) (42)
Estimated Fair Value 1,017 1,008
US States and Political Subdivisions Debt Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 1,211,841 1,284,245
Gross Unrealized Gains 967 283
Gross Unrealized Losses (145,210) (178,816)
Estimated Fair Value 1,067,598 1,105,712
Corporate Debt Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 475,052 459,792
Gross Unrealized Gains 0 0
Gross Unrealized Losses (36,018) (37,483)
Estimated Fair Value 439,034 422,309
Collateralized Mortgage Obligations [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 141,587 147,155
Gross Unrealized Gains 0 0
Gross Unrealized Losses (11,137) (13,122)
Estimated Fair Value 130,450 134,033
Mortgage-Backed Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 238,775 242,527
Gross Unrealized Gains 33 18
Gross Unrealized Losses (26,234) (29,847)
Estimated Fair Value 212,574 212,698
Amortized Cost, Held to Maturity 444,431 457,325
Gross Unrealized Gains, Held to Maturity 0 0
Gross Unrealized Losses, Held to Maturity (52,078) (57,480)
Debt Securities, Held-to-Maturity, Fair Value 392,353 399,845
Commercial Mortgage Backed Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost 651,767 631,604
Gross Unrealized Gains 0 0
Gross Unrealized Losses (80,104) (79,082)
Estimated Fair Value 571,663 552,522
Amortized Cost, Held to Maturity 863,281 863,931
Gross Unrealized Gains, Held to Maturity 0 0
Gross Unrealized Losses, Held to Maturity (130,607) (138,727)
Debt Securities, Held-to-Maturity, Fair Value $ 732,674 725,204
Debt Securities [Member]    
Schedule of Investments [Line Items]    
Amortized Cost   2,992,513
Gross Unrealized Gains   301
Gross Unrealized Losses   (346,047)
Estimated Fair Value   $ 2,646,767