Investments - Fair Values and Unrealized Losses by Investment Category and by Duration of Securities' Continuous Unrealized Loss Position (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Investments, Unrealized Loss Position
Gross unrealized loss	$ 1,115	$ 16
Corporate
Investments, Unrealized Loss Position
Gross unrealized loss	661	13
States, municipalities and political subdivisions
Investments, Unrealized Loss Position
Gross unrealized loss	433	3
Commercial mortgage-backed
Investments, Unrealized Loss Position
Gross unrealized loss	13	0
United States government
Investments, Unrealized Loss Position
Gross unrealized loss	5	0
Government-sponsored enterprises
Investments, Unrealized Loss Position
Gross unrealized loss	3	0
Foreign government
Investments, Unrealized Loss Position
Gross unrealized loss	0	0
Fixed maturities
Investments, Unrealized Loss Position
Less than 12 months Fair Value	10,186	1,047
Less than 12 Months, Unrealized Loss	968	15
12 months or more, Fair Value	453	28
12 months or longer, Unrealized Loss	147	1
Total Fair Value	10,639	1,075
Gross unrealized loss	1,115	16
Fixed maturities | Corporate
Investments, Unrealized Loss Position
Less than 12 months Fair Value	5,835	861
Less than 12 Months, Unrealized Loss	535	13
12 months or more, Fair Value	376	15
12 months or longer, Unrealized Loss	126	0
Total Fair Value	6,211	876
Gross unrealized loss	661	13
Fixed maturities | States, municipalities and political subdivisions
Investments, Unrealized Loss Position
Less than 12 months Fair Value	3,831	105
Less than 12 Months, Unrealized Loss	414	2
12 months or more, Fair Value	48	2
12 months or longer, Unrealized Loss	19	1
Total Fair Value	3,879	107
Gross unrealized loss	433	3
Fixed maturities | Commercial mortgage-backed
Investments, Unrealized Loss Position
Less than 12 months Fair Value	225	10
Less than 12 Months, Unrealized Loss	11	0
12 months or more, Fair Value	14	11
12 months or longer, Unrealized Loss	2	0
Total Fair Value	239	21
Gross unrealized loss	13	0
Fixed maturities | United States government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	173	48
Less than 12 Months, Unrealized Loss	5	0
12 months or more, Fair Value	12	0
12 months or longer, Unrealized Loss	0	0
Total Fair Value	185	48
Gross unrealized loss	5	0
Fixed maturities | Government-sponsored enterprises
Investments, Unrealized Loss Position
Less than 12 months Fair Value	101	7
Less than 12 Months, Unrealized Loss	3	0
12 months or more, Fair Value	3	0
12 months or longer, Unrealized Loss	0	0
Total Fair Value	104	7
Gross unrealized loss	3	0
Fixed maturities | Foreign government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	21	16
Less than 12 Months, Unrealized Loss	0	0
12 months or more, Fair Value	0	0
12 months or longer, Unrealized Loss	0	0
Total Fair Value	21	16
Gross unrealized loss	$ 0	$ 0