Investments (Change In Net Unrealized Gains (Losses) On Available-For-Sale Securities Reported In Accumulated Other Comprehensive Income (Loss)) (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Components of Net Unrealized Investment Gains Losses Included in Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification adjustments to net investment (gains) losses, taxes	$ (13)	$ (13)	$ (13)	$ (26)