Investments (Summary Of Components Of Net Investment Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	$ 319,341	$ 326,794	$ 361,818
Interest debited (credited) and other investment expense	(13,196)	(13,861)	(11,474)
Total net investment income	306,145	312,933	350,344
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	216,796	232,287	290,454
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	39,284	29,694	10,190
Short-Term Investments And Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	1,051	1,078	407
Limited Partnerships [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	39,696	42,349	45,464
Dividends From Parent's Shares [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	18,663	18,645	14,029
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income	$ 3,851	$ 2,741	$ 1,274