Investments - Aggregate Contractual or Notional Amounts and Estimated Fair Values Related to Derivative Financial Instruments (Details) - Without Hedge Designation - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Options – purchased \| Options – purchased
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	$ 234	$ 268
Estimated Fair Value, Asset	3	2
Estimated Fair Value, Liability
Futures – short \| Futures – short
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount		167
Estimated Fair Value, Asset		1
Estimated Fair Value, Liability
Warrants
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	1	1
Estimated Fair Value, Asset	1	1
Estimated Fair Value, Liability
Interest rate swaps
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	300	300
Estimated Fair Value, Asset	2	4
Estimated Fair Value, Liability
Currency forwards
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount
Estimated Fair Value, Asset
Estimated Fair Value, Liability
Credit default swap index - purchased
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/Notional Amount	2,200	2,000
Estimated Fair Value, Asset
Estimated Fair Value, Liability