Investments (Gross Unrealized Losses And Fair Value Of Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Less Than Twelve Months
Estimated Fair Value	$ 911,489	$ 535,672
Unrealized Loss	114,773	4,966
Estimated Fair Value	282,330	29,918
Twelve Months or Greater
Unrealized Loss	72,527	437
Estimated Fair Value	1,193,819	565,590
Unrealized Loss	187,300	5,403
Obligations of states and political subdivisions
Less Than Twelve Months
Estimated Fair Value	229,688	13,277
Unrealized Loss	29,945	152
Estimated Fair Value	12,884	2,420
Twelve Months or Greater
Unrealized Loss	2,910	63
Estimated Fair Value	242,572	15,697
Unrealized Loss	32,855	215
U.S. Government agencies
Less Than Twelve Months
Estimated Fair Value	644,366	521,407
Unrealized Loss	81,602	4,802
Estimated Fair Value	264,596	23,295
Twelve Months or Greater
Unrealized Loss	68,884	7
Estimated Fair Value	908,962	544,702
Unrealized Loss	150,486	4,809
Trust preferred securities
Less Than Twelve Months
Estimated Fair Value	0	0
Unrealized Loss	0	0
Estimated Fair Value	3,945	4,203
Twelve Months or Greater
Unrealized Loss	640	367
Estimated Fair Value	3,945	4,203
Unrealized Loss	640	367
Corporate securities
Less Than Twelve Months
Estimated Fair Value	30,222	988
Unrealized Loss	2,741	12
Estimated Fair Value	905	0
Twelve Months or Greater
Unrealized Loss	93	0
Estimated Fair Value	31,127	988
Unrealized Loss	2,834	$ 12
Private Label
Less Than Twelve Months
Estimated Fair Value	7,213
Unrealized Loss	485
Estimated Fair Value	0
Twelve Months or Greater
Unrealized Loss	0
Estimated Fair Value	7,213
Unrealized Loss	$ 485