XML 43 R31.htm IDEA: XBRL DOCUMENT v3.7.0.1
Investments (Narrative) (Details)
$ in Thousands
6 Months Ended
Jun. 30, 2017
USD ($)
Securities
Jun. 30, 2016
USD ($)
Dec. 31, 2016
Securities
Investments [Abstract]      
Fixed income securities with call features, percentage 37.00%    
Fixed income securities with call features, currently callable, percentage 2.10%    
Fixed income securities with call features, currently callable, amount $ 899,100    
Fixed income securities with call features, callable during next 12 months, percentage 1.00%    
Fixed income securities with call features, callable during next 12 months, amount $ 409,500    
Fixed income securities with call features, not callable until within 6 months of stated maturity, percentage 72.00%    
Percentage of fixed maturity portfolio rated investment grade based on NAIC designations 97.00%   97.00%
Number of individual securities with unrealized losses | Securities 956   1,514
Percentage of unrealized losses on fixed maturity securities where securities are rated investment grade 81.00%   86.00%
Investment Holdings [Line Items]      
Scheduled principal repayments, calls and tenders for available for sale securities $ 970,752 $ 1,421,976  
Available For Sale Securities [Member]      
Investment Holdings [Line Items]      
Proceeds from sales of available for sale securities 376,900 186,100  
Fixed Maturity Securities [Member]      
Investment Holdings [Line Items]      
Scheduled principal repayments, calls and tenders for available for sale securities $ 593,800 $ 1,200,000