Investments (Summary Of Net Realized Investment Gains And The Change In Net Unrealized Gains On Investments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Realized gains on investments	$ 12,074	$ 11,484
Realized losses on investments	(165)	(244)
Other-than-temporary impairments, realized losses	0	0
Net realized investment gains	11,909	11,240
Change in net unrealized gains on investments	213,660	20,464
Sales Of fixed maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Realized gains on investments	1,859	7,988
Realized losses on investments	(165)	(244)
Sales Of equity saecurities [Member]
Schedule of Available-for-sale Securities [Line Items]
Realized gains on investments	9,694	2,071
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Realized gains on investments	521	1,425
Realized losses on investments	0	0
Fixed maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Change in net unrealized gains on investments	16,669	(16,396)
Equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Change in net unrealized gains on investments	196,994	36,857
Short-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Change in net unrealized gains on investments	$ (3)	$ 3