Guaranteed Benefit Features (Information On Guaranteed Death Benefit Features) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Return of Net Deposits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 111,818	$ 109,856
Net amount at risk	$ 77	$ 72
Average attained age of contract holders	66 years	66 years
Minimum Return [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value	$ 99	$ 100
Net amount at risk	$ 12	$ 12
Average attained age of contract holders	78 years	78 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	$ 27,903	$ 27,650
Net amount at risk	$ 410	$ 390
Average attained age of contract holders	72 years	72 years