Investments - Fair Values and Unrealized Losses by Investment Category and by Duration of Securities' Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Investments, Unrealized Loss Position
Gross unrealized loss	$ 776	$ 908
Corporate
Investments, Unrealized Loss Position
Gross unrealized loss	526	580
States, municipalities and political subdivisions
Investments, Unrealized Loss Position
Gross unrealized loss	226	303
Government-sponsored enterprises
Investments, Unrealized Loss Position
Gross unrealized loss	4	3
Commercial mortgage-backed
Investments, Unrealized Loss Position
Gross unrealized loss	16	16
United States government
Investments, Unrealized Loss Position
Gross unrealized loss	4	5
Foreign government
Investments, Unrealized Loss Position
Gross unrealized loss	0	1
Fixed maturities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	5,698	8,760
Less than 12 Months, Unrealized Loss	215	706
12 months or more, Fair Value	3,340	800
12 months or longer, Unrealized Loss	561	202
Total Fair Value	9,038	9,560
Gross unrealized loss	776	908
Fixed maturities | Corporate
Investments, Unrealized Loss Position
Less than 12 months Fair Value	3,910	5,651
Less than 12 Months, Unrealized Loss	158	412
12 months or more, Fair Value	2,273	661
12 months or longer, Unrealized Loss	368	168
Total Fair Value	6,183	6,312
Gross unrealized loss	526	580
Fixed maturities | States, municipalities and political subdivisions
Investments, Unrealized Loss Position
Less than 12 months Fair Value	1,287	2,600
Less than 12 Months, Unrealized Loss	48	274
12 months or more, Fair Value	890	77
12 months or longer, Unrealized Loss	178	29
Total Fair Value	2,177	2,677
Gross unrealized loss	226	303
Fixed maturities | Government-sponsored enterprises
Investments, Unrealized Loss Position
Less than 12 months Fair Value	263	123
Less than 12 Months, Unrealized Loss	3	3
12 months or more, Fair Value	7	3
12 months or longer, Unrealized Loss	1	0
Total Fair Value	270	126
Gross unrealized loss	4	3
Fixed maturities | Commercial mortgage-backed
Investments, Unrealized Loss Position
Less than 12 months Fair Value	107	215
Less than 12 Months, Unrealized Loss	5	13
12 months or more, Fair Value	116	14
12 months or longer, Unrealized Loss	11	3
Total Fair Value	223	229
Gross unrealized loss	16	16
Fixed maturities | United States government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	121	146
Less than 12 Months, Unrealized Loss	1	3
12 months or more, Fair Value	52	41
12 months or longer, Unrealized Loss	3	2
Total Fair Value	173	187
Gross unrealized loss	4	5
Fixed maturities | Foreign government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	10	25
Less than 12 Months, Unrealized Loss	0	1
12 months or more, Fair Value	2	4
12 months or longer, Unrealized Loss	0	0
Total Fair Value	12	29
Gross unrealized loss	$ 0	$ 1