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, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments [Abstract]
Balance as of beginning-of-year	$ 358	$ 411	$ 363
Increases attributable to:
Credit losses on securities for which an OTTI was not previously recognized	5	13	83
Credit losses on securities for which an OTTI was previously recognized	2	7	16
Decreases attributable to:
Securities sold, paid down or matured	(28)	(73)	(51)
Balance as of end-of-year	$ 337	$ 358	$ 411