XML 77 R51.htm IDEA: XBRL DOCUMENT v2.4.0.6
Investment gains/losses and other-than-temporary impairment losses on investments - Other-than-temporary impairment losses (Detail) (USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Schedule of Other than Temporary Impairments [Line Items]    
Other-than-temporary investment losses $ 337 $ 506
Equity Securities [Member]
   
Schedule of Other than Temporary Impairments [Line Items]    
Other-than-temporary investment losses   506
Fixed Maturities [Member]
   
Schedule of Other than Temporary Impairments [Line Items]    
Other-than-temporary investment losses $ 337