Condensed Financial Information of Registrant (Schedule Of Condensed Financial Information Of Registrant, Statements Of Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net cash provided by operating activities	$ 383,434	$ 341,405	$ 291,678
Fixed maturity securities available for sale in nature:
Purchases	(706,224)	(734,397)	(1,077,638)
Sales	189,306	100,709	396,766
Equity securities available for sale in nature
Purchases	1,026,827	831,310	714,113
Sales	954,755	679,571	696,138
Other, net	10,105	1,934	3,605
Net cash used in investing activities	(222,436)	(185,597)	(226,720)
Cash flows from financing activities:
Dividends paid to shareholders	(138,478)	(137,886)	(137,201)
Employee taxes paid with shares related to share-based compensation	0	0	(3,292)
Proceeds from stock options exercised	358	2,162	1,632
Net proceeds from issuance of senior notes	0	371,011	0
Payoff of principal on loan and credit facilities	0	(320,000)	0
Proceeds from bank loan	0	0	30,000
Net cash used in financing activities	(138,120)	(84,713)	(108,861)
Net increase (decrease) in cash	22,878	71,095	(43,903)
Cash:
Beginning of year	291,413	220,318	264,221
End of year	314,291	291,413	220,318
SUPPLEMENTAL CASH FLOW DISCLOSURE
Interest paid	16,586	9,863	3,531
Parent Company [Member]
Cash flows from operating activities:
Net cash provided by operating activities	(16,108)	(14,503)	4,731
Cash flows from investing activities:
Capital contribution to subsidiaries	(541)	(140,125)	(30,125)
Distributions received from special purpose entities	5,998	5,243	4,898
Dividends received from subsidiaries	135,000	109,000	110,800
Fixed maturity securities available for sale in nature:
Purchases	0	0	(1,060)
Sales	0	1,614	0
Equity securities available for sale in nature
Purchases	22,286	22,406	64,807
Sales	33,052	18,876	73,942
Calls	0	4,000	0
Decrease (increase) in short-term investments	18,065	(20,607)	515
Other, net	605	310	1,614
Net cash used in investing activities	169,893	(44,095)	95,777
Cash flows from financing activities:
Dividends paid to shareholders	(138,478)	(137,886)	(137,201)
Employee taxes paid with shares related to share-based compensation	0	0	(3,292)
Proceeds from stock options exercised	358	2,162	1,632
Net proceeds from issuance of senior notes	0	371,011	0
Payoff of principal on loan and credit facilities	0	(180,000)	0
Proceeds from bank loan	0	0	30,000
Net cash used in financing activities	(138,120)	55,287	(108,861)
Net increase (decrease) in cash	15,665	(3,311)	(8,353)
Cash:
Beginning of year	8,475	11,786	20,139
End of year	24,140	8,475	11,786
SUPPLEMENTAL CASH FLOW DISCLOSURE
Interest paid	16,586	9,435	2,397
Income taxes paid	$ 4,296	$ 346
Income taxes (refunded)			$ (339)