Investments (Summary Of Aggregate Market Value And Gross Unrealized Depreciation Of Fixed Maturity And Equity Securities, By Security Type) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Market Value, Total	$ 1,414,865	$ 2,571,006
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(60,629)	(100,332)
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	894,404	1,925,177
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(26,847)	(62,697)
Available for sale securities, Greater than 12 months, Market Value	520,461	645,829
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(33,782)	(37,635)
Available-for-sale Securities, Market Value, Total	1,414,865	2,571,006
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(60,629)	(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	54,980	216,352
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(66)	(712)
Available for sale securities, Greater than 12 months, Market Value	698	692
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation		(6)
Available-for-sale Securities, Market Value, Total	55,678	217,044
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(66)	(718)
Obligations of US States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	4,469	6,434
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(16)	(84)
Available for sale securities, Greater than 12 months, Market Value	7,014	4,917
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(827)	(806)
Available-for-sale Securities, Market Value, Total	11,483	11,351
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(843)	(890)
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	471,961	866,715
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(20,832)	(49,034)
Available for sale securities, Greater than 12 months, Market Value	242,718	307,215
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(18,770)	(21,691)
Available-for-sale Securities, Market Value, Total	714,679	1,173,930
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(39,602)	(70,725)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	20,482	102,506
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(77)	(791)
Available for sale securities, Greater than 12 months, Market Value	31,533	28,048
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(210)	(272)
Available-for-sale Securities, Market Value, Total	52,015	130,554
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(287)	(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	17,323	26,483
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(188)	$ (511)
Available for sale securities, Greater than 12 months, Market Value
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation
Available-for-sale Securities, Market Value, Total	17,323	$ 26,483
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(188)	(511)
Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	100,416	320,285
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(901)	(3,094)
Available for sale securities, Greater than 12 months, Market Value	114,503	150,095
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(1,024)	(3,509)
Available-for-sale Securities, Market Value, Total	214,919	470,380
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(1,925)	(6,603)
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	22,510	61,498
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(638)	(2,182)
Available for sale securities, Greater than 12 months, Market Value	57,790	77,911
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(7,144)	(6,243)
Available-for-sale Securities, Market Value, Total	80,300	139,409
Available-for-sale Securities, Gross Unrealized Depreciation, Total	(7,782)	(8,425)
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities, Less than 12 months, Market Value	202,263	324,904
Available for sale securities, Less than 12 months, Gross Unrealized Depreciation	(4,129)	(6,289)
Available for sale securities, Greater than 12 months, Market Value	66,205	76,951
Available for sale securities, Greater than 12 months, Gross Unrealized Depreciation	(5,807)	(5,108)
Available-for-sale Securities, Market Value, Total	268,468	401,855
Available-for-sale Securities, Gross Unrealized Depreciation, Total	$ (9,936)	$ (11,397)

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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