Investment Securities, HTM Credit Quality Indicators (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	$ 3,570,901	$ 3,602,576
US Treasury Securities
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	996	996
US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	1,618,922	1,628,088
Residential Mortgage-Backed Securities [Member] | US Government Sponsored-Enterprise Insured Loans
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	811,047	823,630
Residential Mortgage-Backed Securities [Member] | Government National Mortgage Association (GNMA) [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	38,021	39,123
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	298,196	302,817
Commercial Mortgage-Backed Securities [Member] | US Government Sponsored-Enterprise Insured Loans
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	761,410	763,370
Commercial Mortgage-Backed Securities [Member] | Government National Mortgage Association (GNMA) [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss	$ 42,309	$ 44,552