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, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
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	$ 37	$ 43	$ 74
Additions where no OTTI was previously recorded	22	9	8
Additions where an OTTI was previously recorded	5	3	12
Reductions for securities sold during the period	(36)	(18)	(51)
Balance of credit losses related to securities still held-end of period	$ 28	$ 37	$ 43