Investments (Summary Of Components Of Net Investment Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	$ 79,863	$ 82,814	$ 240,677	$ 261,197
Interest debited (credited) and other investment expense	(3,521)	(4,489)	(8,887)	(11,281)
Total net investment income	76,342	78,325	231,790	249,916
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	55,495	58,248	164,248	178,006
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	8,849	8,726	29,281	20,366
Short-Term Investments And Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	330	296	758	890
Limited Partnerships [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	9,096	12,399	29,940	44,753
Dividends From Parent's Shares [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	4,666	4,665	13,997	13,979
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	$ 1,427	$ (1,520)	$ 2,453	$ 3,203