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, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Balance as of beginning-of-period	$ 355	$ 378	$ 430
Increases attributable to:
Credit losses on securities for which an OTTI was not previously recognized	13	5	13
Credit losses on securities for which an OTTI was previously recognized	3	2	7
Decreases attributable to:
Securities sold, paid down or matured	(160)	(30)	(72)
Balance as of end-of-period	$ 211	$ 355	$ 378