Investments (Summary Of Aggregate Market Value And Gross Unrealized Depreciation Of Fixed Maturity And Equity Securities, By Security Type) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	$ 2,495,611	$ 3,764,340
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(113,584)	(132,430)
Fixed maturity securities, Greater than 12 months, Market Value	1,599,859	639,825
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(55,428)	(40,762)
Fixed maturity securities, Total, Market Value	4,095,470	4,404,165
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(169,012)	(173,192)
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	2,445,326	3,637,310
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(109,516)	(123,833)
Fixed maturity securities, Greater than 12 months, Market Value	1,525,865	639,825
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(47,549)	(40,762)
Fixed maturity securities, Total, Market Value	3,971,191	4,277,135
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(157,065)	(164,595)
U.S. Treasury Securities And Obligations Of U.S. Government Agencies And Corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	13,187	74,847
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(20)	(1,033)
Fixed maturity securities, Greater than 12 months, Market Value	26,897	8,751
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(284)	(645)
Fixed maturity securities, Total, Market Value	40,084	83,598
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(304)	(1,678)
Obligations Of U.S. States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	20,428	92,760
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(242)	(4,852)
Fixed maturity securities, Greater than 12 months, Market Value	18,199	39,689
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(384)	(4,170)
Fixed maturity securities, Total, Market Value	38,627	132,449
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(626)	(9,022)
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	1,245,830	959,396
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(55,388)	(22,331)
Fixed maturity securities, Greater than 12 months, Market Value	362,320	75,946
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(7,518)	(4,759)
Fixed maturity securities, Total, Market Value	1,608,150	1,035,342
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(62,906)	(27,090)
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	192,253	5,494
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(1,230)	(6)
Fixed maturity securities, Greater than 12 months, Market Value		1,128
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(416)
Fixed maturity securities, Total, Market Value	192,253	6,622
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(1,230)	(422)
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	28,191	51
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(123)
Fixed maturity securities, Greater than 12 months, Market Value	9,777	11,353
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(306)	(1,007)
Fixed maturity securities, Total, Market Value	37,968	11,404
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(429)	(1,007)
Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	141,807	1,220,845
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(172)	(40,420)
Fixed maturity securities, Greater than 12 months, Market Value	678,972	264,640
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(11,401)	(9,755)
Fixed maturity securities, Total, Market Value	820,779	1,485,485
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(11,573)	(50,175)
Non-Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		1,758
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(22)
Fixed maturity securities, Greater than 12 months, Market Value	266	1,541
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(57)	(204)
Fixed maturity securities, Total, Market Value	266	3,299
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(57)	(226)
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	235,725	409,252
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(15,415)	(20,350)
Fixed maturity securities, Greater than 12 months, Market Value	139,200	85,029
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(11,451)	(8,997)
Fixed maturity securities, Total, Market Value	374,925	494,281
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(26,866)	(29,347)
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	567,905	872,907
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(36,926)	(34,819)
Fixed maturity securities, Greater than 12 months, Market Value	290,234	151,748
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(16,148)	(10,809)
Fixed maturity securities, Total, Market Value	858,139	1,024,655
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(53,074)	(45,628)
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	50,285	127,030
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(4,068)	(8,597)
Fixed maturity securities, Greater than 12 months, Market Value	73,994
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(7,879)
Fixed maturity securities, Total, Market Value	124,279	127,030
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	$ (11,947)	$ (8,597)