v3.3.1.900
Investments - Fair Value and Unrealized Losses (Details)
$ in Thousands
Dec. 31, 2015
USD ($)
security
Dec. 31, 2014
USD ($)
security
Fair value    
Fixed Maturities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value $ 1,294,157 $ 525,149
Fixed Maturities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 592,418 588,017
Fixed Maturities, Continuous Unrealized Loss Position, Fair Value 1,886,575 1,113,166
Investments, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 1,299,062  
Investments, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 592,418  
Investments, Continuous Unrealized Loss Position, Fair Value 1,891,480  
Unrealized losses    
Fixed Maturities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (46,935) (18,113)
Fixed Maturities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (78,282) (20,898)
Fixed Maturities, Continuous Unrealized Loss Position, Accumulated Loss (125,217) $ (39,011)
Investments, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses (47,030)  
Investments, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses (78,282)  
Investments, Continuous Unrealized Loss Position, Accumulated Loss $ (125,312)  
Fixed Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | security 93 46
Fixed Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | security 270 141
U.S. treasury bonds    
Fair value    
Fixed Maturities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value $ 1,119  
Fixed Maturities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 0  
Fixed Maturities, Continuous Unrealized Loss Position, Fair Value 1,119  
Unrealized losses    
Fixed Maturities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (16)  
Fixed Maturities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 0  
Fixed Maturities, Continuous Unrealized Loss Position, Accumulated Loss (16)  
U.S. agency bonds – mortgage-backed    
Fair value    
Fixed Maturities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 443,331 $ 84,264
Fixed Maturities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 170,053 441,601
Fixed Maturities, Continuous Unrealized Loss Position, Fair Value 613,384 525,865
Unrealized losses    
Fixed Maturities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (4,113) (806)
Fixed Maturities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (6,077) (9,782)
Fixed Maturities, Continuous Unrealized Loss Position, Accumulated Loss (10,190) (10,588)
Non-U.S. government and supranational bonds    
Fair value    
Fixed Maturities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 6,958 43,712
Fixed Maturities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 22,586 2,522
Fixed Maturities, Continuous Unrealized Loss Position, Fair Value 29,544 46,234
Unrealized losses    
Fixed Maturities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (365) (2,822)
Fixed Maturities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (4,219) (306)
Fixed Maturities, Continuous Unrealized Loss Position, Accumulated Loss (4,584) (3,128)
Asset-backed securities    
Fair value    
Fixed Maturities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 89,838  
Fixed Maturities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 0  
Fixed Maturities, Continuous Unrealized Loss Position, Fair Value 89,838  
Unrealized losses    
Fixed Maturities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (1,089)  
Fixed Maturities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 0  
Fixed Maturities, Continuous Unrealized Loss Position, Accumulated Loss (1,089)  
Corporate bonds    
Fair value    
Fixed Maturities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 752,911 397,173
Fixed Maturities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 399,779 143,894
Fixed Maturities, Continuous Unrealized Loss Position, Fair Value 1,152,690 541,067
Unrealized losses    
Fixed Maturities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (41,352) (14,485)
Fixed Maturities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (67,986) (10,810)
Fixed Maturities, Continuous Unrealized Loss Position, Accumulated Loss (109,338) $ (25,295)
Other investments    
Fair value    
Investments, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value 4,905  
Investments, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 0  
Investments, Continuous Unrealized Loss Position, Fair Value 4,905  
Unrealized losses    
Investments, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses (95)  
Investments, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses 0  
Investments, Continuous Unrealized Loss Position, Accumulated Loss $ (95)