XML 123 R63.htm IDEA: XBRL DOCUMENT v2.4.0.6
Mortgage Loans, Sorted by Applicable Credit Quality Indicators, Internal rating (Detail) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Mortgage Loans on Real Estate [Line Items]    
Mortgage Loans $ 1,612.3 [1] $ 1,516.8
Aa
   
Mortgage Loans on Real Estate [Line Items]    
Mortgage Loans 10.9 19.0
A
   
Mortgage Loans on Real Estate [Line Items]    
Mortgage Loans 712.6 744.4
Baa
   
Mortgage Loans on Real Estate [Line Items]    
Mortgage Loans 855.0 732.9
Ba
   
Mortgage Loans on Real Estate [Line Items]    
Mortgage Loans 20.7 20.5
B
   
Mortgage Loans on Real Estate [Line Items]    
Mortgage Loans $ 13.1 $ 0
[1] Amortized cost for fixed maturity securities and mortgage loans represents original cost reduced by repayments, write-downs from other-than-temporary declines in fair value, amortization of premiums, and accretion of discounts.