Derivative Financial Instruments - Collateral and Credit Default Swaps (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Securities pledged as collateral
Derivatives, Fair Value [Line Items]
Cash collateral held for securities loan agreement	$ 6	$ 7
Collateral Securities Repledged, Delivered, or Used	159	102
Over the Counter | Payables under securities loan agreement, including collateral held
Derivatives, Fair Value [Line Items]
Cash collateral held for securities loan agreement	47	50
Exchange Cleared | Payables under securities loan agreement, including collateral held
Derivatives, Fair Value [Line Items]
Cash collateral held for securities loan agreement	$ 19	$ 62