Investments (Summary Of Net Realized Investment Gains (Losses) And The Change In Net Unrealized Gains On Investments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Gain (Loss) on Investments [Line Items]
Realized gains	$ 18,850	$ 9,509	$ 47,266	$ 27,707
Realized losses	(6,315)	(226)	(18,129)	(5,812)
Gains (losses) on securities measured at fair value through net income	4,706	(3,178)	9,283	(10,219)
Other-than-temporary impairment losses recognized in net income	(3,675)	0	(12,080)	(5,092)
Net realized investment gains	17,241	6,105	38,420	11,676
Change in net unrealized gains on investments	255,844	(351,332)	592,691	(186,669)
Sales Of Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	699	770	967	2,338
Realized losses	(142)	(97)	(555)	(221)
Sales Of Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	17,798	7,000	45,526	22,956
Realized losses	(1,780)	(113)	(2,498)	(272)
Other [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	353	1,739	773	2,413
Realized losses	(718)	(16)	(2,996)	(227)
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Change in net unrealized gains on investments	213,026	(286,551)	452,982	(180,213)
Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment losses recognized in net income	(3,700)		(12,100)	(5,100)
Change in net unrealized gains on investments	42,786	(64,792)	139,744	(6,447)
Short-Term Investments [Member]
Gain (Loss) on Investments [Line Items]
Change in net unrealized gains on investments	$ 32	$ 11	$ (35)	$ (9)