Investments (Schedule Of Changes in Amount Of Credit Losses Of OTTI Recognized In Net Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments [Abstract]
Balance as of beginning of period	$ 382	$ 380	$ 404
Increases attributable to:
Credit losses on securities for which an OTTI was not previously recognized	84	19	4
Credit losses on securities for which an OTTI was previously recognized	17	16	16
Decreases attributable to:
Securities sold, paid down or matured	(53)	(33)	(44)
Balance as of end of period	$ 430	$ 382	$ 380