Investments - Analysis of Cost or Amortized Cost, Gross Unrealized Gains and Losses and Fair Value for Investments (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale
Total	$ 14,709	$ 14,361
Gross unrealized gain	89	117
Gross unrealized loss	714	687
Fixed maturities, at fair value	14,084	13,791
Corporate
Debt Securities, Available-for-sale
Total	8,002	7,836
Gross unrealized gain	60	70
Gross unrealized loss	463	454
Fixed maturities, at fair value	7,599	7,452
States, municipalities and political subdivisions
Debt Securities, Available-for-sale
Total	4,872	4,867
Gross unrealized gain	28	44
Gross unrealized loss	232	208
Fixed maturities, at fair value	4,668	4,703
Government-sponsored enterprises
Debt Securities, Available-for-sale
Total	1,424	1,227
Gross unrealized gain	1	3
Gross unrealized loss	4	6
Fixed maturities, at fair value	1,421	1,224
Asset-backed
Debt Securities, Available-for-sale
Total	200	203
Gross unrealized gain	0	0
Gross unrealized loss	11	16
Fixed maturities, at fair value	189	187
United States government
Debt Securities, Available-for-sale
Total	182	203
Gross unrealized gain	0	0
Gross unrealized loss	4	3
Fixed maturities, at fair value	178	200
Foreign government
Debt Securities, Available-for-sale
Total	29	25
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fixed maturities, at fair value	$ 29	$ 25