Guaranteed Benefit Features (Information On Guaranteed Death Benefit Features) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Return of Net Deposits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 97,611	$ 101,601
Net amount at risk	$ 340	$ 71
Average attained age of contract holders	66 years	65 years
Minimum Return [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 87	$ 92
Net amount at risk	$ 13	$ 13
Average attained age of contract holders	78 years	77 years
Guaranteed minimum return	5.00%	5.00%
Anniversary Contract Value [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 24,457	$ 25,763
Net amount at risk	$ 663	$ 384
Average attained age of contract holders	72 years	71 years