Investments (Summary Of Aggregate Market Value And Gross Unrealized Depreciation Of Fixed Maturity And Equity Securities, By Security Type) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		$ 2,495,611
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(113,584)
Fixed maturity securities, Greater than 12 months, Market Value		1,599,859
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(55,428)
Fixed maturity securities, Total, Market Value	$ 4,269,794	4,095,470
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(221,587)	(169,012)
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	2,819,476	2,445,326	$ 2,819,476
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(118,097)	(109,516)	(118,097)
Fixed maturity securities, Greater than 12 months, Market Value	1,352,447	1,525,865	1,352,447
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(85,569)	(47,549)	(85,569)
Fixed maturity securities, Total, Market Value	4,171,923	3,971,191	4,171,923
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	(203,666)	(157,065)	(203,666)
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	201
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(20)	(1)
Fixed maturity securities, Greater than 12 months, Market Value		26,897	1,844
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(284)	(69)
Fixed maturity securities, Total, Market Value		40,084	2,045
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(304)	(70)
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	20,162
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(242)	(316)
Fixed maturity securities, Greater than 12 months, Market Value		18,199	35,460
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(384)	(1,207)
Fixed maturity securities, Total, Market Value		38,627	55,622
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(626)	(1,523)
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		1,245,830	1,323,515
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(55,388)	(51,785)
Fixed maturity securities, Greater than 12 months, Market Value		362,320	425,091
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(7,518)	(24,611)
Fixed maturity securities, Total, Market Value		1,608,150	1,748,606
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(62,906)	(76,396)
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value	89,526	192,253	89,526
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation	(674)	(1,230)	(674)
Fixed maturity securities, Greater than 12 months, Market Value	44,765		44,765
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation	(880)		(880)
Fixed maturity securities, Total, Market Value	134,291	192,253	134,291
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total	$ (1,554)	(1,230)	(1,554)
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		28,191	44,260
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(123)	(795)
Fixed maturity securities, Greater than 12 months, Market Value		9,777
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(306)
Fixed maturity securities, Total, Market Value		37,968	44,260
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(429)	(795)
Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		141,807	343,504
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(172)	(2,182)
Fixed maturity securities, Greater than 12 months, Market Value		678,972	382,730
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(11,401)	(3,983)
Fixed maturity securities, Total, Market Value		820,779	726,234
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(11,573)	(6,165)
Non-Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value			176
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation			(2)
Fixed maturity securities, Greater than 12 months, Market Value		266	44
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(57)	(44)
Fixed maturity securities, Total, Market Value		266	220
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(57)	(46)
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		235,725	299,055
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(15,415)	(22,177)
Fixed maturity securities, Greater than 12 months, Market Value		139,200	183,387
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(11,451)	(22,705)
Fixed maturity securities, Total, Market Value		374,925	482,442
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(26,866)	(44,882)
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		567,905	699,077
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(36,926)	(40,165)
Fixed maturity securities, Greater than 12 months, Market Value		290,234	279,126
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(16,148)	(32,070)
Fixed maturity securities, Total, Market Value		858,139	978,203
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		(53,074)	(72,235)
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturity securities, Less than 12 months, Market Value		50,285
Fixed maturity securities, duration of unrealized loss, less than 12 months, gross unrealized depreciation		(4,068)
Fixed maturity securities, Greater than 12 months, Market Value		73,994	97,871
Fixed maturity securities, Duration of Unrealized Loss, Greater than 12 months, Gross Unrealized Depreciation		(7,879)	(17,921)
Fixed maturity securities, Total, Market Value		124,279	97,871
Fixed maturity securities, Duration of Unrealized Loss, Total, Gross Unrealized Depreciation, Total		$ (11,947)	$ (17,921)