Investments (Summary Of Unrealized Appreciation (Depreciation) Of Available For Sale, Fixed Maturity And Equity Security Investments) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 5,709,509	$ 5,116,600
Unrealized Appreciation	150,625	149,876
Unrealized Depreciation	(42,018)	(64,555)
Market Value	5,818,116	5,201,921
U.S. Treasury Securities And Obligations Of U.S. Government Agencies And Corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	519,888	72,211
Unrealized Appreciation	698	420
Unrealized Depreciation	(815)	(946)
Market Value	519,771	71,685
Obligation Of U.S. States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	792,193	970,735
Unrealized Appreciation	43,524	40,815
Unrealized Depreciation	(994)	(9,022)
Market Value	834,723	1,002,528
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,010,245	1,669,553
Unrealized Appreciation	41,864	45,355
Unrealized Depreciation	(21,510)	(12,493)
Market Value	2,030,599	1,702,415
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	91,583	38,544
Unrealized Appreciation	821	1,065
Unrealized Depreciation	(87)
Market Value	92,317	39,609
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	40,935	34,855
Unrealized Appreciation	2,750	3,811
Unrealized Depreciation	(1)
Market Value	43,684	38,666
Agency Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	626,511	709,589
Unrealized Appreciation	6,873	6,331
Unrealized Depreciation	(6,842)	(18,521)
Market Value	626,542	697,399
Non-Agency Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	307	859
Unrealized Appreciation	51	113
Unrealized Depreciation		(33)
Market Value	358	939
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	544,947	654,029
Unrealized Appreciation	26,458	28,739
Unrealized Depreciation	(4,274)	(7,941)
Market Value	567,131	674,827
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,082,900	966,225
Unrealized Appreciation	27,586	23,227
Unrealized Depreciation	(7,495)	(15,599)
Market Value	1,102,991	973,853
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15	15
Unrealized Appreciation	1
Unrealized Depreciation		(2)
Market Value	$ 16	$ 13