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	$ 337	$ 358	$ 411
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	2	2	7
Decreases attributable to:
Securities sold, paid down or matured	(148)	(28)	(73)
Balance as of end-of-period	$ 204	$ 337	$ 358