Investments (Roll-Forward Of Pre-Tax Credit Losses Related To Fixed Maturities For Which Portion Of Other-Than-Temporary Impairment Was Recognized In Other Comprehensive Income) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Roll-Forward Of Pre-Tax Credit Losses Related To Fixed Maturities For Which Portion Of OTTI Was Recognized In OCI
Balance of credit losses related to securities still held-beginning of period	$ 28	$ 37	$ 43
Additions where no OTTI was previously recorded	41	22	9
Additions where an OTTI was previously recorded	9	5	3
Reductions for securities sold during the period	(25)	(36)	(18)
Balance of credit losses related to securities still held-end of period	$ 53	$ 28	$ 37