XML 48 R37.htm IDEA: XBRL DOCUMENT v3.8.0.1
Investments - Pretax Credit Loss Component Reflected in Retained Earnings on Fixed Maturity Securities (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]        
Beginning balance of credit losses on fixed maturity securities $ 30 $ 41 $ 36 $ 53
Reductions for securities sold during the period (2) (2) (8) (14)
Reductions for securities the Company intends to sell or more likely than not will be required to sell   (1)   (1)
Ending balance of credit losses on fixed maturity securities $ 28 $ 38 $ 28 $ 38