Investments - Debt Securities by Maturity (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Net Amortized Cost
Less than one year	$ 1,412
One year through five years	6,823
After five years through ten years	4,627
Greater than ten years	4,297
Net Amortized Cost	22,114	$ 22,063
Fair Value
Less than one year	1,395
One year through five years	6,510
After five years through ten years	4,299
Greater than ten years	3,960
Total	20,822	20,280
Residential mortgage-backed securities
Net Amortized Cost
Debt securities, maturity, without single maturity date	881
Net Amortized Cost	881	845
Fair Value
Debt securities, maturity, without single maturity date	812
Total	812	757
Commercial mortgage-backed securities
Net Amortized Cost
Debt securities, maturity, without single maturity date	1,173
Net Amortized Cost	1,173	1,172
Fair Value
Debt securities, maturity, without single maturity date	1,028
Total	1,028	1,018
Other asset-backed securities
Net Amortized Cost
Debt securities, maturity, without single maturity date	2,901
Net Amortized Cost	2,901	2,940
Fair Value
Debt securities, maturity, without single maturity date	2,818
Total	$ 2,818	$ 2,810