Condensed Financial Information of Registrant (Schedule Of Condensed Financial Information Of Registrant, Statements Of Cash Flow) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net cash provided by operating activities	$ 501,584,000	$ 605,616,000	$ 519,678,000
Cash flows from investing activities:
Capital distribution from subsidiaries	5,200,000	12,100,000	5,200,000
Equity securities available for sale in nature
Purchases	(958,008,000)	(1,230,785,000)	(1,174,759,000)
Sales	943,857,000	1,174,540,000	1,088,701,000
Other, net	9,096,000	20,577,000	6,247,000
Net cash used in investing activities	(373,670,000)	(411,286,000)	(401,201,000)
Cash flows from financing activities:
Dividends paid to shareholders	(140,226,000)	(139,640,000)	(139,071,000)
Proceeds from stock options exercised	215,000	0	701,000
Net cash used in financing activities	(140,836,000)	(140,249,000)	(138,370,000)
Net increase (decrease) in cash	(12,922,000)	54,081,000	(19,893,000)
Cash:
Beginning of year	348,479,000	294,398,000	314,291,000
End of year	335,557,000	348,479,000	294,398,000
SUPPLEMENTAL CASH FLOW DISCLOSURE
Interest paid	16,616,000	16,599,000	16,586,000
Income taxes paid (refunded), net	69,467,000	52,659,000	(14,564,000)
Parent Company
Cash flows from operating activities:
Net cash provided by operating activities	(36,662,000)	(17,339,000)	(5,392,000)
Cash flows from investing activities:
Capital contribution to subsidiaries	0	(30,000,000)	(125,000)
Capital distribution from subsidiaries	0	0	30,068,567
Distributions received from special purpose entities	5,199,000	12,129,000	5,153,000
Dividends received from subsidiaries	191,000,000	121,000,000	114,431,000
Equity securities available for sale in nature
Purchases	(13,151,000)	(54,571,000)	(39,966,000)
Sales	38,092,000	67,965,000	74,663,000
(Increase) decrease in short-term investments	(16,172,000)	25,088,000	(25,213,000)
Other, net	791,000	254,000	376,000
Net cash used in investing activities	205,759,000	141,865,000	159,388,000
Cash flows from financing activities:
Dividends paid to shareholders	(140,226,000)	(139,640,000)	(139,071,000)
Proceeds from stock options exercised	215,000	0	701,000
Net cash used in financing activities	(140,011,000)	(139,640,000)	(138,370,000)
Net increase (decrease) in cash	29,086,000	(15,114,000)	15,626,000
Cash:
Beginning of year	24,652,000	39,766,000	24,140,000
End of year	53,738,000	24,652,000	39,766,000
SUPPLEMENTAL CASH FLOW DISCLOSURE
Interest paid	16,590,000	16,586,000	16,586,000
Income taxes paid (refunded), net	$ 18,841,000	$ (20,552,000)	$ (12,391,000)