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Securities (Amortized Cost and Fair Value of Debt Securities Held to Maturity) (Details) - USD ($)
$ in Thousands
Sep. 30, 2023
Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]    
Securities Held to Maturity, Gross Amortized cost $ 2,727,945 $ 2,852,495
Securities Held to Maturity, Gross unrealized gains   774
Securities Held to Maturity, Gross unrealized losses 297,658 237,871
Securities Held to Maturity, Fair value 2,430,287 2,615,398
U.S. Treasury And Government Agency Securities [Member]    
Schedule of Held-to-maturity Securities [Line Items]    
Securities Held to Maturity, Gross Amortized cost 418,323 426,454
Securities Held to Maturity, Gross unrealized gains   21
Securities Held to Maturity, Gross unrealized losses 60,006 49,044
Securities Held to Maturity, Fair value 358,317 377,431
Municipal Obligations [Member]    
Schedule of Held-to-maturity Securities [Line Items]    
Securities Held to Maturity, Gross Amortized cost 667,809 698,908
Securities Held to Maturity, Gross unrealized gains   753
Securities Held to Maturity, Gross unrealized losses 39,068 26,558
Securities Held to Maturity, Fair value 628,741 673,103
Residential Mortgage-Backed Securities [Member]    
Schedule of Held-to-maturity Securities [Line Items]    
Securities Held to Maturity, Gross Amortized cost 673,898 734,478
Securities Held to Maturity, Gross unrealized losses 88,902 72,532
Securities Held to Maturity, Fair value 584,996 661,946
Commercial Mortgage-Backed Securities [Member]    
Schedule of Held-to-maturity Securities [Line Items]    
Securities Held to Maturity, Gross Amortized cost 933,260 948,691
Securities Held to Maturity, Gross unrealized losses 107,231 87,211
Securities Held to Maturity, Fair value 826,029 861,480
Collateralized Mortgage Obligations [Member]    
Schedule of Held-to-maturity Securities [Line Items]    
Securities Held to Maturity, Gross Amortized cost 34,655 43,964
Securities Held to Maturity, Gross unrealized losses 2,451 2,526
Securities Held to Maturity, Fair value $ 32,204 $ 41,438