Guaranteed Benefit Features (Summary Of Guaranteed Death Benefit Liabilities) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Guaranteed Benefit Features [Abstract]
Balance as of beginning-of-year	$ 115	$ 89
Changes in reserves	22	59
Benefits paid	(31)	(17)
Balance as of end-of-period	$ 106	$ 131