Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Total	$ 1,603,297	$ 1,384,607
Gross Unrealized Gains	1,385	28,961
Gross Unrealized Losses	107,455	5,403
Estimated Fair Value	1,497,227	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	264,756	263,809
Gross Unrealized Gains	509	8,622
Gross Unrealized Losses	21,768	215
Estimated Fair Value	243,497	272,216
U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Total	1,298,690	1,080,381
Gross Unrealized Gains	817	18,739
Gross Unrealized Losses	83,011	4,809
Estimated Fair Value	1,216,496	1,094,311
Private label
Debt Securities, Available-for-sale [Line Items]
Total	8,070	8,555
Gross Unrealized Gains	0	553
Gross Unrealized Losses	186	0
Estimated Fair Value	7,884	9,108
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
Total	4,579	4,570
Gross Unrealized Gains	0	0
Gross Unrealized Losses	779	367
Estimated Fair Value	3,800	4,203
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Total	27,202	27,292
Gross Unrealized Gains	59	1,047
Gross Unrealized Losses	1,711	12
Estimated Fair Value	$ 25,550	$ 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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A savings certificate entitling the Entity (that is, bearer) to receive interest at an established maturity date, based upon a fixed interest rate. A certificate of deposit may be issued in any denomination. Certificates of deposit are generally issued by commercial banks and, therefore, insured by the FDIC (up to the prescribed limit). Certificates of deposit generally restrict holders from withdrawing funds on demand without the incurrence of penalties. Generally, only certificates of deposit with original maturities of three months or less qualify as cash equivalents. Original maturity means original maturity to the entity holding the investment. As a related example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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