Investments (Schedule Of Changes in Amount Of Credit Losses Of OTTI Recognized In Net Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Investments [Abstract]
Balance as of beginning of year	$ 424	$ 390
Increases attributable to:
Credit losses on securities for which an OTTI was not previously recognized	1	34
Credit losses on securities for which an OTTI was previously recognized	16	23
Decreases attributable to:
Securities sold	(4)	(37)
Balance as of end of period	$ 437	$ 410