Investments (Duration Of Gross Unrealized Losses On Fixed Maturity Securities And Equity Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	$ 64,288	$ 8,844
Gross unrealized losses on securities, 12 months or more, fair value	13,806	24,980
Gross unrealized losses on securities, fair Value, total	78,094	33,824
Gross unrealized losses on securities, less than 12 months, unrealized losses	(1,639)	(264)
Gross unrealized losses on securities, 12 months or more, unrealized losses	(985)	(1,830)
Gross unrealized losses on securities, unrealized losses, total	(2,624)	(2,094)
Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	2,018,037	720,465
Gross unrealized losses on securities, 12 months or more, fair value	94,115	240,810
Gross unrealized losses on securities, fair Value, total	2,112,152	961,275
Gross unrealized losses on securities, less than 12 months, unrealized losses	(89,332)	(13,740)
Gross unrealized losses on securities, 12 months or more, unrealized losses	(11,547)	(6,345)
Gross unrealized losses on securities, unrealized losses, total	(100,879)	(20,085)
Fixed maturity securities | Corporate
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	1,636,457	640,641
Gross unrealized losses on securities, 12 months or more, fair value	54,029	113,918
Gross unrealized losses on securities, fair Value, total	1,690,486	754,559
Gross unrealized losses on securities, less than 12 months, unrealized losses	(85,247)	(13,132)
Gross unrealized losses on securities, 12 months or more, unrealized losses	(10,665)	(3,482)
Gross unrealized losses on securities, unrealized losses, total	(95,912)	(16,614)
Fixed maturity securities | Residential mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	260,620	22,337
Gross unrealized losses on securities, 12 months or more, fair value	11,147	61,682
Gross unrealized losses on securities, fair Value, total	271,767	84,019
Gross unrealized losses on securities, less than 12 months, unrealized losses	(3,179)	(71)
Gross unrealized losses on securities, 12 months or more, unrealized losses	(230)	(1,083)
Gross unrealized losses on securities, unrealized losses, total	(3,409)	(1,154)
Non-redeemable preferred stocks | Equity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	63,665	8,844
Gross unrealized losses on securities, 12 months or more, fair value	13,806	24,784
Gross unrealized losses on securities, fair Value, total	77,471	33,628
Gross unrealized losses on securities, less than 12 months, unrealized losses	(1,632)	(264)
Gross unrealized losses on securities, 12 months or more, unrealized losses	(985)	(1,829)
Gross unrealized losses on securities, unrealized losses, total	(2,617)	(2,093)
Common stocks | Equity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	623	0
Gross unrealized losses on securities, 12 months or more, fair value	0	196
Gross unrealized losses on securities, fair Value, total	623	196
Gross unrealized losses on securities, less than 12 months, unrealized losses	(7)	0
Gross unrealized losses on securities, 12 months or more, unrealized losses	0	(1)
Gross unrealized losses on securities, unrealized losses, total	(7)	(1)
United States Government and government agencies and authorities | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	90,008	34,551
Gross unrealized losses on securities, 12 months or more, fair value	5,564	21,488
Gross unrealized losses on securities, fair Value, total	95,572	56,039
Gross unrealized losses on securities, less than 12 months, unrealized losses	(465)	(188)
Gross unrealized losses on securities, 12 months or more, unrealized losses	(72)	(241)
Gross unrealized losses on securities, unrealized losses, total	(537)	(429)
State, municipalities and political subdivisions | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	6,881	3,050
Gross unrealized losses on securities, 12 months or more, fair value	0	4,633
Gross unrealized losses on securities, fair Value, total	6,881	7,683
Gross unrealized losses on securities, less than 12 months, unrealized losses	(94)	(282)
Gross unrealized losses on securities, 12 months or more, unrealized losses	0	(71)
Gross unrealized losses on securities, unrealized losses, total	(94)	(353)
Foreign governments | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	24,071	19,886
Gross unrealized losses on securities, 12 months or more, fair value	22,239	37,741
Gross unrealized losses on securities, fair Value, total	46,310	57,627
Gross unrealized losses on securities, less than 12 months, unrealized losses	(347)	(67)
Gross unrealized losses on securities, 12 months or more, unrealized losses	(376)	(1,390)
Gross unrealized losses on securities, unrealized losses, total	(723)	(1,457)
Asset-backed | Fixed maturity securities
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses on securities, less than 12 months, fair value	0	0
Gross unrealized losses on securities, 12 months or more, fair value	1,136	1,348
Gross unrealized losses on securities, fair Value, total	1,136	1,348
Gross unrealized losses on securities, less than 12 months, unrealized losses	0	0
Gross unrealized losses on securities, 12 months or more, unrealized losses	(204)	(78)
Gross unrealized losses on securities, unrealized losses, total	$ (204)	$ (78)