v2.3.0.15
Investments (Available-For-Sale Investments) (Details) (USD $)
In Thousands
Sep. 30, 2011
Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost$ 5,223,979$ 5,256,980
Equity securities, Amortized Cost1,092,662996,088
Available-for-sale securities, Amortized Cost6,808,3716,578,404
Available-for-sale investments, Gross Unrealized Holding Gains904,292956,338
Available-for-sale investments, Gross Unrealized Holding Losses(22,484)(36,634)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses(12,640)(19,571)
Total fixed maturities, Estimated Fair Value5,576,5845,431,226
Available-for-sale equity investments, Estimated Fair Value1,609,1991,721,971
Short-term investments, Estimated Fair Value491,756325,340
Available-for-sale investments, Estimated Fair Value7,677,5397,478,537
U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost284,438300,555
Available-for-sale investments, Gross Unrealized Holding Gains23,73320,832
Available-for-sale investments, Gross Unrealized Holding Losses(12)(49)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Total fixed maturities, Estimated Fair Value308,159321,338
Obligations Of States, Municipalities And Political Subdivisions [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost2,743,3592,767,169
Available-for-sale investments, Gross Unrealized Holding Gains176,16361,620
Available-for-sale investments, Gross Unrealized Holding Losses(1,359)(29,450)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Total fixed maturities, Estimated Fair Value2,918,1632,799,339
Foreign Governments [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost683,747550,755
Available-for-sale investments, Gross Unrealized Holding Gains56,61624,662
Available-for-sale investments, Gross Unrealized Holding Losses0(2,599)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Total fixed maturities, Estimated Fair Value740,363572,818
Residential Mortgage-Backed Securities [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost392,534409,415
Available-for-sale investments, Gross Unrealized Holding Gains31,35529,664
Available-for-sale investments, Gross Unrealized Holding Losses(13)(1,738)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses(5,922)(11,778)
Total fixed maturities, Estimated Fair Value417,954425,563
Asset-Backed Securities [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost16,72321,704
Available-for-sale investments, Gross Unrealized Holding Gains8371,052
Available-for-sale investments, Gross Unrealized Holding Losses(8)0
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Total fixed maturities, Estimated Fair Value17,55222,756
Public Utilities [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost70,48295,770
Available-for-sale investments, Gross Unrealized Holding Gains5,6256,674
Available-for-sale investments, Gross Unrealized Holding Losses00
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Total fixed maturities, Estimated Fair Value76,107102,444
Convertible Bonds [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost 16,725
Available-for-sale investments, Gross Unrealized Holding Gains 0
Available-for-sale investments, Gross Unrealized Holding Losses 0
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses 0
Total fixed maturities, Estimated Fair Value 16,725
All Other Corporate Bonds [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost1,032,6961,094,887
Available-for-sale investments, Gross Unrealized Holding Gains74,63683,752
Available-for-sale investments, Gross Unrealized Holding Losses(2,328)(603)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses(6,718)(7,793)
Total fixed maturities, Estimated Fair Value1,098,2861,170,243
Fixed Maturities [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Fixed maturities, Amortized Cost5,223,9795,256,980
Available-for-sale investments, Gross Unrealized Holding Gains368,965228,256
Available-for-sale investments, Gross Unrealized Holding Losses(3,720)(34,439)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses(12,640)(19,571)
Total fixed maturities, Estimated Fair Value5,576,5845,431,226
Insurance Companies, Banks And Trusts [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Equity securities, Amortized Cost371,004388,848
Available-for-sale investments, Gross Unrealized Holding Gains250,441323,634
Available-for-sale investments, Gross Unrealized Holding Losses(9,050)(1,496)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Available-for-sale equity investments, Estimated Fair Value612,395710,986
Industrial, Consumer And All Other [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Equity securities, Amortized Cost721,658607,240
Available-for-sale investments, Gross Unrealized Holding Gains284,859404,444
Available-for-sale investments, Gross Unrealized Holding Losses(9,713)(699)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Available-for-sale equity investments, Estimated Fair Value996,8041,010,985
Equity Securities [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Equity securities, Amortized Cost1,092,662996,088
Available-for-sale investments, Gross Unrealized Holding Gains535,300728,078
Available-for-sale investments, Gross Unrealized Holding Losses(18,763)(2,195)
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Available-for-sale equity investments, Estimated Fair Value1,609,1991,721,971
Short-Term Investments [Member]
  
Schedule of Available-for-sale Securities [Line Items]  
Short-term investments, Amortized Cost491,730325,336
Available-for-sale investments, Gross Unrealized Holding Gains274
Available-for-sale investments, Gross Unrealized Holding Losses(1)0
Available-for-sale investments, Unrealized Other-Than-Temporary Impairment Losses00
Short-term investments, Estimated Fair Value$ 491,756$ 325,340