Fair Value Measurements (Details 3) (USD $)
In Thousands, unless otherwise specified
6 Months Ended
Jun. 30, 2012
Dec. 31, 2011
Quantitative information about Level 3 fair value measurements    
Fixed maturity securities available for sale, at fair value $ 2,816,250 $ 2,682,142
Level 3 [Member]
   
Quantitative information about Level 3 fair value measurements    
Fixed maturity securities available for sale, at fair value $ 44,999 $ 43,759
Fair Value of Fixed maturity securities on Valuation Technique Market comparable  
Fair Value Measurements Unobservable Inputs Spread adjustment  
Fair value input Spread adjustment percentage of Weighted Average for Fair Value Measurement 1.90%  
Level 3 [Member] | Maximum [Member]
   
Quantitative information about Level 3 fair value measurements    
Fair value inputs spread adjustment, range 3.67%  
Level 3 [Member] | Minimum [Member]
   
Quantitative information about Level 3 fair value measurements    
Fair value inputs spread adjustment, range 0.46%