Investments (Summary Of Net Realized Investment Gains And The Change In Net Unrealized Gains On Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Gain (Loss) on Investments [Line Items]
Realized gains	$ 168,163	$ 74,978	$ 93,304
Realized losses	(61,683)	(28,978)	(30,152)
Other-than-temporary impairment losses recognized in net income	(44,481)	(4,784)	(4,706)
Net realized investment gains	106,480	46,000	63,152
Change in net unrealized gains on investments	(457,584)	981,035	261,995
Sales Of Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	3,073	8,417	13,772
Realized losses	(4,598)	(18,136)	(25,168)
Sales Of Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	156,987	51,356	73,592
Realized losses	(1,232)	(802)	(278)
Other [Member]
Gain (Loss) on Investments [Line Items]
Realized gains	8,103	15,205	5,940
Realized losses	(11,372)	(5,256)	0
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment losses recognized in net income	0	(304)	(1,882)
Change in net unrealized gains on investments	(137,435)	480,350	(403,610)
Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment losses recognized in net income	(44,481)	(4,480)	(2,824)
Change in net unrealized gains on investments	(320,277)	500,673	665,599
Short-Term Investments [Member]
Gain (Loss) on Investments [Line Items]
Change in net unrealized gains on investments	$ 128	$ 12	$ 6