Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$ 3,594,076	$ 3,410,899
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	19,875	25,618
Estimated Fair Value	3,594,076	3,410,899
Investments held in Rabbi Trust	39,004	35,093
Derivative assets	129,799	161,621
Assets, Fair Value Disclosure	3,782,754	3,633,231
Liabilities Held-In-Trust, Fair Value Disclosure	39,004	35,093
Derivative Liability	178,603	254,417
Total liabilities	217,607	289,510
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	811,736	814,887
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	811,736	814,887
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	255,039	300,370
Corporate Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	255,039	300,370
Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,135,442	788,885
Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,135,442	788,885
Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	858,992	989,875
Mortgage-Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	858,992	989,875
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	532,867	516,882
Commercial Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	532,867	516,882
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	0	0
Estimated Fair Value	0	0
Investments held in Rabbi Trust	39,004	35,093
Derivative assets	1,179	1,682
Assets, Fair Value Disclosure	40,183	36,775
Liabilities Held-In-Trust, Fair Value Disclosure	39,004	35,093
Derivative Liability	970	1,596
Total liabilities	39,974	36,689
Fair Value, Inputs, Level 1 [Member] \| US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] \| Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] \| Mortgage-Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] \| Commercial Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	19,875	25,618
Estimated Fair Value	3,594,076	3,410,899
Investments held in Rabbi Trust	0	0
Derivative assets	128,620	159,939
Assets, Fair Value Disclosure	3,742,571	3,596,456
Liabilities Held-In-Trust, Fair Value Disclosure	0	0
Derivative Liability	177,633	252,821
Total liabilities	177,633	252,821
Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	811,736	814,887
Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	255,039	300,370
Fair Value, Inputs, Level 2 [Member] \| Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,135,442	788,885
Fair Value, Inputs, Level 2 [Member] \| Mortgage-Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	858,992	989,875
Fair Value, Inputs, Level 2 [Member] \| Commercial Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	532,867	516,882
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgages Held-for-sale, Fair Value Disclosure	0	0
Estimated Fair Value	0	0
Investments held in Rabbi Trust	0	0
Derivative assets	0	0
Assets, Fair Value Disclosure	0	0
Liabilities Held-In-Trust, Fair Value Disclosure	0	0
Derivative Liability	0	0
Total liabilities	0	0
Fair Value, Inputs, Level 3 [Member] \| US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Mortgage-Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Commercial Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	$ 0	$ 0