Guaranteed Benefit Features (Information On Guaranteed Death Benefit Features) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 134,738	$ 125,350
Return of Net Deposits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	109,856	101,601
Net amount at risk	$ 72	$ 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	$ 100	$ 92
Net amount at risk	$ 12	$ 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	$ 27,650	$ 25,763
Net amount at risk	$ 390	$ 384
Average attained age of contract holders	72 years	71 years