Investments - Debt Securities by Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Net Amortized Cost
Less than one year	$ 1,304
One year through five years	7,318
After five years through ten years	4,408
Greater than ten years	4,268
Net Amortized Cost	22,267	$ 22,063
Fair Value
Less than one year	1,288
One year through five years	6,942
After five years through ten years	4,078
Greater than ten years	3,904
Total	20,903	20,280
Residential mortgage-backed securities
Net Amortized Cost
Debt securities, maturity, without single maturity date	863
Net Amortized Cost	863	845
Fair Value
Debt securities, maturity, without single maturity date	785
Total	785	757
Commercial mortgage-backed securities
Net Amortized Cost
Debt securities, maturity, without single maturity date	1,137
Net Amortized Cost	1,137	1,172
Fair Value
Debt securities, maturity, without single maturity date	998
Total	998	1,018
Other asset-backed securities
Net Amortized Cost
Debt securities, maturity, without single maturity date	2,969
Net Amortized Cost	2,969	2,940
Fair Value
Debt securities, maturity, without single maturity date	2,908
Total	$ 2,908	$ 2,810