Investments (Credit Quality Indicators For Residential Mortgage Loans) (Details) - Residential [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Mortgage Loans Credit Quality [Line Items]
Carrying value of mortgage loans on real estate	$ 733	$ 248
Percentage of total mortgage loans on real estate	100.00%	100.00%
Performing [Member]
Mortgage Loans Credit Quality [Line Items]
Carrying value of mortgage loans on real estate	$ 716	$ 247
Percentage of total mortgage loans on real estate	97.70%	99.60%
Nonperforming [Member]
Mortgage Loans Credit Quality [Line Items]
Carrying value of mortgage loans on real estate	$ 17	$ 1
Percentage of total mortgage loans on real estate	2.30%	0.40%