Investments - Fair Values and Unrealized Losses by Investment Category and by Duration of Securities' Continuous Unrealized Loss Position (Detail) - Fixed maturities - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Investments, Unrealized Loss Position
Less than 12 months Fair Value	$ 3,797	$ 1,047
Less than 12 Months, Unrealized Loss	232	15
12 months or more, Fair Value	112	28
12 months or longer, Unrealized Loss	13	1
Total Fair Value	3,909	1,075
Gross unrealized loss	245	16
Corporate
Investments, Unrealized Loss Position
Less than 12 months Fair Value	2,603	861
Less than 12 Months, Unrealized Loss	157	13
12 months or more, Fair Value	78	15
12 months or longer, Unrealized Loss	9	0
Total Fair Value	2,681	876
Gross unrealized loss	166	13
States, municipalities and political subdivisions
Investments, Unrealized Loss Position
Less than 12 months Fair Value	977	105
Less than 12 Months, Unrealized Loss	72	2
12 months or more, Fair Value	21	2
12 months or longer, Unrealized Loss	4	1
Total Fair Value	998	107
Gross unrealized loss	76	3
Commercial mortgage-backed
Investments, Unrealized Loss Position
Less than 12 months Fair Value	128	10
Less than 12 Months, Unrealized Loss	2	0
12 months or more, Fair Value	10	11
12 months or longer, Unrealized Loss	0	0
Total Fair Value	138	21
Gross unrealized loss	2	0
United States government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	72	48
Less than 12 Months, Unrealized Loss	1	0
12 months or more, Fair Value	0	0
12 months or longer, Unrealized Loss	0	0
Total Fair Value	72	48
Gross unrealized loss	1	0
Foreign government
Investments, Unrealized Loss Position
Less than 12 months Fair Value	7	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	7	16
Gross unrealized loss	0	0
Government-sponsored enterprises
Investments, Unrealized Loss Position
Less than 12 months Fair Value	10	7
Less than 12 Months, Unrealized Loss	0	0
12 months or more, Fair Value	3	0
12 months or longer, Unrealized Loss	0	0
Total Fair Value	13	7
Gross unrealized loss	$ 0	$ 0