Guaranteed Benefit Features (Summary Of Guaranteed Death Benefit Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Guaranteed Benefit Features [Abstract]
Balance as of beginning-of-year	$ 115	$ 89
Changes in reserves	15	6
Benefits paid	(14)	(6)
Balance as of end-of-period	$ 116	$ 89