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	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
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 [Roll Forward]
Balance of credit losses related to securities still held – beginning of period	$ 28	$ 37
Additions where no OTTI was previously recorded	3	2
Additions where an OTTI was previously recorded	1	2
Reductions for securities sold during the period	(10)	(6)
Balance of credit losses related to securities still held – end of period	$ 22	$ 35