Investments (Fair Values And Unrealized Losses By Investment Category And By The Duration Of The Securities' Continuous Unrealized Loss Position) (Details) - Fixed Maturities - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investments, Unrealized Loss Position
Less than 12 months fair value	$ 340	$ 3,031
Less than 12 Months, Unrealized losses	4	70
12 months or more fair value	183	1,149
12 Months or more, unrealized losses	3	58
Total fair value	523	4,180
Total Unrealized Losses	7	128
Corporate Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	199	2,082
Less than 12 Months, Unrealized losses	2	51
12 months or more fair value	118	501
12 Months or more, unrealized losses	3	36
Total fair value	317	2,583
Total Unrealized Losses	5	87
States, Municipalities and Political Subdivisions
Investments, Unrealized Loss Position
Less than 12 months fair value	98	823
Less than 12 Months, Unrealized losses	1	18
12 months or more fair value	10	340
12 Months or more, unrealized losses	0	13
Total fair value	108	1,163
Total Unrealized Losses	1	31
Commercial Mortgage Backed Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	6	77
Less than 12 Months, Unrealized losses	0	0
12 months or more fair value	0	64
12 Months or more, unrealized losses	0	2
Total fair value	6	141
Total Unrealized Losses	0	2
Government-Sponsored Enterprises
Investments, Unrealized Loss Position
Less than 12 months fair value	26	49
Less than 12 Months, Unrealized losses	1	1
12 months or more fair value	51	211
12 Months or more, unrealized losses	0	6
Total fair value	77	260
Total Unrealized Losses	1	7
United States Government
Investments, Unrealized Loss Position
Less than 12 months fair value	0	0
Less than 12 Months, Unrealized losses	0	0
12 months or more fair value	4	33
12 Months or more, unrealized losses	0	1
Total fair value	4	33
Total Unrealized Losses	0	$ 1
Foreign government
Investments, Unrealized Loss Position
Less than 12 months fair value	11
Less than 12 Months, Unrealized losses	0
12 months or more fair value	0
12 Months or more, unrealized losses	0
Total fair value	11
Total Unrealized Losses	$ 0