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, 2020	Dec. 31, 2019
Investments, Unrealized Loss Position
Less than 12 months fair value	$ 406	$ 340
Less than 12 Months, Unrealized losses	8	4
12 months or more fair value	54	183
12 Months or more, unrealized losses	2	3
Total fair value	460	523
Total Unrealized Losses	10	7
Corporate Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	330	199
Less than 12 Months, Unrealized losses	5	2
12 months or more fair value	46	118
12 Months or more, unrealized losses	2	3
Total fair value	376	317
Total Unrealized Losses	7	5
States, Municipalities and Political Subdivisions
Investments, Unrealized Loss Position
Less than 12 months fair value	31	98
Less than 12 Months, Unrealized losses	2	1
12 months or more fair value	2	10
12 Months or more, unrealized losses	0	0
Total fair value	33	108
Total Unrealized Losses	2	1
Commercial Mortgage Backed Securities
Investments, Unrealized Loss Position
Less than 12 months fair value	23	6
Less than 12 Months, Unrealized losses	1	0
12 months or more fair value	6	0
12 Months or more, unrealized losses	0	0
Total fair value	29	6
Total Unrealized Losses	1	0
United States Government
Investments, Unrealized Loss Position
Less than 12 months fair value	12	0
Less than 12 Months, Unrealized losses	0	0
12 months or more fair value	0	4
12 Months or more, unrealized losses	0	0
Total fair value	12	4
Total Unrealized Losses	0	0
Foreign government
Investments, Unrealized Loss Position
Less than 12 months fair value	10	11
Less than 12 Months, Unrealized losses	0	0
12 months or more fair value	0	0
12 Months or more, unrealized losses	0	0
Total fair value	10	11
Total Unrealized Losses	$ 0	0
Government-Sponsored Enterprises
Investments, Unrealized Loss Position
Less than 12 months fair value		26
Less than 12 Months, Unrealized losses		1
12 months or more fair value		51
12 Months or more, unrealized losses		0
Total fair value		77
Total Unrealized Losses		$ 1