Investments (Details 11) (USD $)
In Thousands, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Schedule Carrying Amount Of Mortgage Loans By Maturity    
Mortgages loans Carrying Amount $ 582,017 $ 604,772
Percentage of Total Carrying Amount 100.00% 100.00%
Due In One Year Or Less [Member]
   
Schedule Carrying Amount Of Mortgage Loans By Maturity    
Mortgages loans Carrying Amount 5,572 2,356
Percentage of Total Carrying Amount 1.00%  
Due After One Year Through Five Years [Member]
   
Schedule Carrying Amount Of Mortgage Loans By Maturity    
Mortgages loans Carrying Amount 181,974 153,822
Percentage of Total Carrying Amount 32.00% 25.00%
Due After Five Years Through Ten Years [Member]
   
Schedule Carrying Amount Of Mortgage Loans By Maturity    
Mortgages loans Carrying Amount 235,378 255,615
Percentage of Total Carrying Amount 40.00% 42.00%
Due After Ten Years [Member]
   
Schedule Carrying Amount Of Mortgage Loans By Maturity    
Mortgages loans Carrying Amount $ 159,093 $ 192,979
Percentage of Total Carrying Amount 27.00% 33.00%