Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Total	$ 1,573,131	$ 1,479,545
Gross Unrealized Gains	5,752	2,870
Gross Unrealized Losses	116,088	144,278
Estimated Fair Value	1,462,795	1,338,137
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total	225,155	228,456
Gross Unrealized Gains	595	371
Gross Unrealized Losses	13,805	16,089
Estimated Fair Value	211,945	212,738
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Total	1,310,067	1,211,484
Gross Unrealized Gains	5,111	2,362
Gross Unrealized Losses	101,113	125,753
Estimated Fair Value	1,214,065	1,088,093
Private label
Debt Securities, Available-for-sale [Line Items]
Total	6,405	6,997
Gross Unrealized Gains	0	0
Gross Unrealized Losses	109	293
Estimated Fair Value	6,296	6,704
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
Total	4,604	4,599
Gross Unrealized Gains	0	0
Gross Unrealized Losses	89	321
Estimated Fair Value	4,515	4,278
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Total	26,900	28,009
Gross Unrealized Gains	46	137
Gross Unrealized Losses	972	1,822
Estimated Fair Value	$ 25,974	$ 26,324