Guaranteed Benefit Features (Summary Of Guaranteed Death Benefit Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Guaranteed Benefit Features [Abstract]
Balance as of beginning-of-year	$ 161	$ 100	$ 110
Changes in reserves	(24)	77	8
Benefits paid	(20)	(16)	(18)
Balance as of end-of-period	$ 117	$ 161	$ 100