Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Total	$ 1,613,536	$ 1,479,545
Gross Unrealized Gains	1,212	2,870
Gross Unrealized Losses	158,063	144,278
Estimated Fair Value	1,456,685	1,338,137
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total	226,055	228,456
Gross Unrealized Gains	154	371
Gross Unrealized Losses	18,423	16,089
Estimated Fair Value	207,786	212,738
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Total	1,348,238	1,211,484
Gross Unrealized Gains	1,027	2,362
Gross Unrealized Losses	137,752	125,753
Estimated Fair Value	1,211,513	1,088,093
Private label
Debt Securities, Available-for-sale [Line Items]
Total	6,709	6,997
Gross Unrealized Gains	0	0
Gross Unrealized Losses	262	293
Estimated Fair Value	6,447	6,704
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
Total	4,602	4,599
Gross Unrealized Gains	0	0
Gross Unrealized Losses	9	321
Estimated Fair Value	4,593	4,278
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Total	27,932	28,009
Gross Unrealized Gains	31	137
Gross Unrealized Losses	1,617	1,822
Estimated Fair Value	$ 26,346	$ 26,324