Condensed Financial Information of Registrant (Schedule Of Condensed Financial Information Of Registrant, Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments, at fair value:
Fixed maturity securities	$ 2,814,553	$ 2,880,003
Equity securities	357,327	315,362
Short-term investments	375,680	185,277
Total investments	3,547,560	3,380,642
Cash	220,318	264,221	$ 289,907	$ 266,508
Accrued investment income	41,205	42,747
Current income taxes	0	9,041
Deferred income taxes	45,277	23,231
Other assets	25,414	16,826
Total assets	4,788,718	4,628,645
Liabilities
Notes payable	320,000	290,000
Accounts payable and accrued expenses	112,334	122,571
Other liabilities	229,335	199,187
Total liabilities	3,036,316	2,807,760
Shareholders’ equity:
Common stock	95,529	90,985
Additional paid-in capital	0	8,870
Retained earnings	1,656,873	1,721,030
Total shareholders’ equity	1,752,402	1,820,885	1,875,446
Total liabilities and shareholders’ equity	4,788,718	4,628,645
Amortized cost on fixed maturities trading investments	2,795,410	2,804,275
Cost - equity security trading investments	331,770	313,528
Cost - short-term investments	375,700	185,353
Parent Company [Member]
Investments, at fair value:
Fixed maturity securities	1,605	571
Equity securities	122,717	127,572
Short-term investments	629	1,144
Investment in subsidiaries	1,810,663	1,819,426
Total investments	1,935,614	1,948,713
Cash	11,786	20,139	$ 52,326	$ 46,332
Accrued investment income	189	208
Amounts receivable from affiliates	226	220
Current income taxes	0	8,894
Deferred income taxes	2,702	10,524
Income tax receivable from affiliates	35,237	5,917
Other assets	414	2,981
Total assets	1,986,168	1,997,596
Liabilities
Notes payable	180,000	150,000
Accounts payable and accrued expenses	348	0
Amounts payable to affiliates	36	25
Income tax payable to affiliates	39,539	26,439
Current income taxes	10,200	0
Other liabilities	3,643	247
Total liabilities	233,766	176,711
Shareholders’ equity:
Common stock	95,529	90,985
Additional paid-in capital	0	8,870
Retained earnings	1,656,873	1,721,030
Total shareholders’ equity	1,752,402	1,820,885
Total liabilities and shareholders’ equity	1,986,168	1,997,596
Amortized cost on fixed maturities trading investments	1,609	557
Cost - equity security trading investments	113,943	131,217
Cost - short-term investments	$ 629	$ 1,144