Guaranteed Benefit Features (Summary Of Guaranteed Death Benefit Liabilities) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Guaranteed Benefit Features [Abstract]
Balance as of beginning-of-year	$ 115	$ 89
Changes in reserves	22	17
Benefits paid	(24)	(11)
Balance as of end-of-period	$ 113	$ 95