v2.4.0.6
FAIR VALUE MEASUREMENTS (DETAILS 2) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities $ 10,940,100 $ 10,482,897
Equity securities 677,560 349,254
Other investments 699,320 519,296
Other assets (see Note 7) 38,175 6,641
Other liabilities (see Note 7) 2,035 14,986
Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 10,940,100 10,482,897
Equity securities 677,560 349,254
Other investments 699,320 519,296
Other assets (see Note 7) 38,175 6,641
Total assets 12,355,155 11,358,088
Other liabilities (see Note 7) 2,035 14,986
US Government and Agency [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,148,267 860,120
US Government and Agency [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,148,267 860,120
Non-US Government [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,212,451 772,798
Non-US Government [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,212,451 772,798
Corporate Debt [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 3,609,591 4,162,908
Corporate Debt [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 3,609,591 4,162,908
Agency RMBS [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 2,636,634 2,593,582
Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 2,636,634 2,593,582
CMBS [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 312,691 474,785
CMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 312,691 474,785
Non-Agency RMBS [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 165,713 244,202
Non-Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 165,713 244,202
ABS [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 632,042 661,843
ABS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 632,042 661,843
Municipals [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,222,711 712,659
Municipals [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,222,711 712,659
Level 1 [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 765,519 588,281
Equity securities 561,436 271,451
Other investments 0 0
Other assets (see Note 7) 0 0
Total assets 1,326,955 859,732
Other liabilities (see Note 7) 0 0
Level 1 [Member] | US Government and Agency [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 765,519 588,281
Level 1 [Member] | Non-US Government [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 1 [Member] | Corporate Debt [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 1 [Member] | Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 1 [Member] | CMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 1 [Member] | Non-Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 1 [Member] | ABS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 1 [Member] | Municipals [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 2 [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 10,123,703 9,830,210
Equity securities 116,124 77,803
Other investments 286,516 0
Other assets (see Note 7) 38,175 6,641
Total assets 10,564,518 9,914,654
Other liabilities (see Note 7) 2,035 14,986
Level 2 [Member] | US Government and Agency [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 382,748 271,839
Level 2 [Member] | Non-US Government [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,212,451 772,798
Level 2 [Member] | Corporate Debt [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 3,608,041 4,161,358
Level 2 [Member] | Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 2,636,634 2,593,582
Level 2 [Member] | CMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 312,691 474,785
Level 2 [Member] | Non-Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 165,713 224,524
Level 2 [Member] | ABS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 582,714 618,665
Level 2 [Member] | Municipals [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,222,711 712,659
Level 3 [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 50,878 64,406
Equity securities 0 0
Other investments 412,804 519,296
Other assets (see Note 7) 0 0
Total assets 463,682 583,702
Other liabilities (see Note 7) 0 0
Level 3 [Member] | US Government and Agency [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 3 [Member] | Non-US Government [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 3 [Member] | Corporate Debt [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 1,550 1,550
Level 3 [Member] | Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 3 [Member] | CMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 0
Level 3 [Member] | Non-Agency RMBS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 0 19,678
Level 3 [Member] | ABS [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities 49,328 43,178
Level 3 [Member] | Municipals [Member] | Fair Value Measurements Recurring [Member]
   
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Fixed maturities $ 0 $ 0