Investments - Debt Securities with a Decline in Fair Value from Amortized Cost (Details) $ in Millions	Jun. 30, 2024 USD ($) position	Dec. 31, 2023 USD ($) position
Total
Total Fair Value, including held for sale assets	$ 6,712	$ 6,633
Total Amortized Cost, including held for sale assets	7,493	7,319
Total Unrealized Depreciation, including held for sale assets	$ (781)	$ (686)
Total Number of Issues, including held for sale assets | position	2,491	2,353
Investment grade | Debt securities
One year or less
Fair Value, including held for sale assets	$ 718	$ 330
Amortized Cost, including held for sale assets	730	338
Unrealized Depreciation, including held for sale assets	$ (12)	$ (8)
Number of Issues, including held for sale assets | position	301	142
More than one year
Fair Value, including held for sale assets	$ 5,273	$ 5,441
Amortized Cost, including held for sale assets	5,971	6,036
Unrealized Depreciation, including held for sale assets	$ (698)	$ (595)
Number of Issues, including held for sale assets | position	1,530	1,590
Below investment grade | Debt securities
One year or less
Fair Value, including held for sale assets	$ 123	$ 161
Amortized Cost, including held for sale assets	127	170
Unrealized Depreciation, including held for sale assets	$ (4)	$ (9)
Number of Issues, including held for sale assets | position	334	135
More than one year
Fair Value, including held for sale assets	$ 598	$ 701
Amortized Cost, including held for sale assets	665	775
Unrealized Depreciation, including held for sale assets	$ (67)	$ (74)
Number of Issues, including held for sale assets | position	326	486