Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Total	$ 1,676,594	$ 1,384,607
Gross Unrealized Gains	98	28,961
Gross Unrealized Losses	187,300	5,403
Estimated Fair Value	1,489,392	1,408,165
Certificates of deposit, at carrying value	1,000	1,000
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total	282,823	263,809
Gross Unrealized Gains	28	8,622
Gross Unrealized Losses	32,855	215
Estimated Fair Value	249,996	272,216
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Total	1,354,218	1,080,381
Gross Unrealized Gains	70	18,739
Gross Unrealized Losses	150,486	4,809
Estimated Fair Value	1,203,802	1,094,311
Private label
Debt Securities, Available-for-sale [Line Items]
Total	7,813	8,555
Gross Unrealized Gains	0	553
Gross Unrealized Losses	485	0
Estimated Fair Value	7,328	9,108
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
Total	4,585	4,570
Gross Unrealized Gains	0	0
Gross Unrealized Losses	640	367
Estimated Fair Value	3,945	4,203
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Total	27,155	27,292
Gross Unrealized Gains	0	1,047
Gross Unrealized Losses	2,834	12
Estimated Fair Value	$ 24,321	$ 28,327

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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