Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Total	$ 1,545,352	$ 1,570,449
Gross Unrealized Gains	4,142	2,417
Gross Unrealized Losses	132,686	151,560
Estimated Fair Value	1,416,808	1,421,306
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total	197,752	199,131
Gross Unrealized Gains	241	139
Gross Unrealized Losses	15,569	15,519
Estimated Fair Value	182,424	183,751
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Total	1,311,090	1,334,755
Gross Unrealized Gains	3,710	1,993
Gross Unrealized Losses	116,007	134,667
Estimated Fair Value	1,198,793	1,202,081
Private label
Debt Securities, Available-for-sale [Line Items]
Total	5,081	5,096
Gross Unrealized Gains	0	0
Gross Unrealized Losses	134	163
Estimated Fair Value	4,947	4,933
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
Total	4,606	4,605
Gross Unrealized Gains	58	141
Gross Unrealized Losses	0	0
Estimated Fair Value	4,664	4,746
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Total	26,823	26,862
Gross Unrealized Gains	133	144
Gross Unrealized Losses	976	1,211
Estimated Fair Value	$ 25,980	$ 25,795