Condensed Financial Information Of Registrant (Schedule Of Condensed Financial Information Of Registrant, Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Investments, at fair value:
Short-term investments	$ 236,444	$ 143,371
Total investments	3,062,421	3,155,257
Cash	211,393	181,388	185,505	35,396
Accrued investment income	32,541	36,885
Current income taxes	0	25,719
Deferred income taxes	6,511	26,499
Other assets	11,232	16,502
Total assets	4,070,006	4,203,364
LIABILITIES AND SHAREHOLDERS' EQUITY
Notes payable	140,000	267,210
Accounts payable and accrued expenses	94,743	106,662
Other liabilities	149,007	167,093
Total liabilities	2,212,523	2,408,549
Shareholders' equity:
Common stock	76,634	74,188
Additional paid -in capital	538	78
Accumulated other comprehensive loss	0	(740)
Retained earnings	1,780,311	1,721,289
Total shareholders' equity	1,857,483	1,794,815	1,770,946
Total liabilities and shareholders' equity	4,070,006	4,203,364
Equity securities amortized cost	388,417	336,757
Cost Short Term Investments	236,433	143,378
Parent Company [Member]
Investments, at fair value:
Equity securities trading	20,282	16,518
Short-term investments	26,817	5,366
Investments in subsidiaries	1,787,047	1,591,638
Total investments	1,834,146	1,613,522
Cash	29,219	41,606	45,344	2,389
Accrued investment income	17	13
Amounts receivable from affiliates	200	189
Current income taxes	22	25,759
Deferred income taxes	1,654
Income tax receivable from affiliates	12,833	3,630
Dividend receivable from affiliates		270,000
Other assets		4,745
Total assets	1,878,091	1,959,464
LIABILITIES AND SHAREHOLDERS' EQUITY
Notes payable		129,210
Accounts payable and accrued expenses	48	43
Income tax payable to affiliates	20,288	34,464
Deferred income taxes		193
Other liabilities	272	739
Total liabilities	20,608	164,649
Shareholders' equity:
Common stock	76,634	74,188
Additional paid -in capital	538	78
Accumulated other comprehensive loss		(740)
Retained earnings	1,780,311	1,721,289
Total shareholders' equity	1,857,483	1,794,815
Total liabilities and shareholders' equity	1,878,091	1,959,464
Equity securities amortized cost	24,885	18,285
Cost Short Term Investments	$ 26,817	$ 5,366