Investments (Credit Quality Indicators For Residential Mortgage Loans) (Details) - Residential [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of total mortgage loans on real estate	$ 739	$ 248
Percentage of total mortgage loans on real estate	100.00%	100.00%
Performing [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of total mortgage loans on real estate	$ 731	$ 247
Percentage of total mortgage loans on real estate	98.90%	99.60%
Nonperforming [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of total mortgage loans on real estate	$ 8	$ 1
Percentage of total mortgage loans on real estate	1.10%	0.40%