Investments (Summary Of Aggregate Market Value And Gross Unrealized Depreciation Of Fixed Maturity And Equity Securities, By Security Type) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	$ 425,752
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(8,551)
Available for sale securities, Greater than 12 months, Market Value	585,675
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(31,471)
Available-for-sale Securities, Market Value, Total	1,011,427	$ 2,571,006
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(40,022)	(100,332)
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	425,752	1,925,177
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(8,551)	(62,697)
Available for sale securities, Greater than 12 months, Market Value	585,675	645,829
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(31,471)	(37,635)
Available-for-sale Securities, Market Value, Total	1,011,427	2,571,006
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(40,022)	(100,332)
U.S. Treasury Securities And Obligations Of U.S. Government Agencies And Corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	4,759	216,352
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(149)	(712)
Available for sale securities, Greater than 12 months, Market Value		692
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation		(6)
Available-for-sale Securities, Market Value, Total	4,759	217,044
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(149)	(718)
Obligations of U.S. States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value		6,434
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation		(84)
Available for sale securities, Greater than 12 months, Market Value	562	4,917
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(478)	(806)
Available-for-sale Securities, Market Value, Total	562	11,351
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(478)	(890)
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	261,660	866,715
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(4,945)	(49,034)
Available for sale securities, Greater than 12 months, Market Value	293,977	307,215
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(15,294)	(21,691)
Available-for-sale Securities, Market Value, Total	555,637	1,173,930
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(20,239)	(70,725)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	13,337	102,506
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(71)	(791)
Available for sale securities, Greater than 12 months, Market Value	30,016	28,048
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(86)	(272)
Available-for-sale Securities, Market Value, Total	43,353	130,554
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(157)	(1,063)
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	3,470	26,483
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(20)	(511)
Available for sale securities, Greater than 12 months, Market Value	3,352
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(45)
Available-for-sale Securities, Market Value, Total	6,822	26,483
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(65)	(511)
Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	32,558	320,285
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(106)	(3,094)
Available for sale securities, Greater than 12 months, Market Value	107,907	150,095
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(468)	(3,509)
Available-for-sale Securities, Market Value, Total	140,465	470,380
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(574)	(6,603)
Non-agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	29
Available-for-sale Securities, Market Value, Total	29
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	9,456	61,498
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(209)	(2,182)
Available for sale securities, Greater than 12 months, Market Value	66,601	77,911
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(7,788)	(6,243)
Available-for-sale Securities, Market Value, Total	76,057	139,409
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(7,997)	(8,425)
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	100,483	324,904
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(3,051)	(6,289)
Available for sale securities, Greater than 12 months, Market Value	83,260	76,951
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(7,312)	(5,108)
Available-for-sale Securities, Market Value, Total	183,743	401,855
Available-for-sale Securities, Gross Unrealized Depreciation, Total	$ (10,363)	$ (11,397)