Investments - Fair Values and Unrealized Losses by Investment Category and by Duration of Securities' Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Investments, Unrealized Loss Position
Gross unrealized loss	$ 900	$ 908
Corporate
Investments, Unrealized Loss Position
Gross unrealized loss	608	580
States, municipalities and political subdivisions
Investments, Unrealized Loss Position
Gross unrealized loss	262	303
Government-sponsored enterprises
Investments, Unrealized Loss Position
Gross unrealized loss	8	3
Commercial mortgage-backed
Investments, Unrealized Loss Position
Gross unrealized loss	17	16
United States government
Investments, Unrealized Loss Position
Gross unrealized loss	5	5
Foreign government
Investments, Unrealized Loss Position
Gross unrealized loss	0	1
Fixed maturities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	3,837	8,760
Less than 12 Months, Unrealized Loss	113	706
12 months or more, Fair Value	6,544	800
12 months or longer, Unrealized Loss	787	202
Total Fair Value	10,381	9,560
Gross unrealized loss	900	908
Fixed maturities | Corporate
Investments, Unrealized Loss Position
Less than 12 months Fair Value	2,133	5,651
Less than 12 Months, Unrealized Loss	94	412
12 months or more, Fair Value	4,347	661
12 months or longer, Unrealized Loss	514	168
Total Fair Value	6,480	6,312
Gross unrealized loss	608	580
Fixed maturities | States, municipalities and political subdivisions
Investments, Unrealized Loss Position
Less than 12 months Fair Value	1,042	2,600
Less than 12 Months, Unrealized Loss	11	274
12 months or more, Fair Value	1,897	77
12 months or longer, Unrealized Loss	251	29
Total Fair Value	2,939	2,677
Gross unrealized loss	262	303
Fixed maturities | Government-sponsored enterprises
Investments, Unrealized Loss Position
Less than 12 months Fair Value	502	123
Less than 12 Months, Unrealized Loss	6	3
12 months or more, Fair Value	32	3
12 months or longer, Unrealized Loss	2	0
Total Fair Value	534	126
Gross unrealized loss	8	3
Fixed maturities | Commercial mortgage-backed
Investments, Unrealized Loss Position
Less than 12 months Fair Value	1	215
Less than 12 Months, Unrealized Loss	0	13
12 months or more, Fair Value	208	14
12 months or longer, Unrealized Loss	17	3
Total Fair Value	209	229
Gross unrealized loss	17	16
Fixed maturities | United States government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	144	146
Less than 12 Months, Unrealized Loss	2	3
12 months or more, Fair Value	60	41
12 months or longer, Unrealized Loss	3	2
Total Fair Value	204	187
Gross unrealized loss	5	5
Fixed maturities | Foreign government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	15	25
Less than 12 Months, Unrealized Loss	0	1
12 months or more, Fair Value	0	4
12 months or longer, Unrealized Loss	0	0
Total Fair Value	15	29
Gross unrealized loss	$ 0	$ 1