Investments - Aggregate Contractual or Notional Amounts and Estimated Fair Values Related to Derivative Financial Instruments (Details) - Without Hedge Designation - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Options – purchased | Options – purchased
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	$ 288	$ 202
Estimated Fair Value, Asset	2	1
Estimated Fair Value, Liability
Futures – short | Futures – short
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	133	116
Estimated Fair Value, Asset	1
Estimated Fair Value, Liability
Warrants
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	76	84
Estimated Fair Value, Asset	1	3
Estimated Fair Value, Liability
Interest rate swaps
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	300	300
Estimated Fair Value, Asset	10	13
Estimated Fair Value, Liability
Currency forwards
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount		13
Estimated Fair Value, Asset
Estimated Fair Value, Liability		$ (1)