Investments - Aggregate Contractual or Notional Amounts and Estimated Fair Values Related to Derivative Financial Instruments (Details) - Without hedge designation - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Futures | Options – purchased
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount	$ 142
Asset, estimated fair value	6
Liability, estimated fair value
Futures | Futures – short
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount	102	169
Asset, estimated fair value
Liability, estimated fair value	(1)
Warrants
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount	117	117
Asset, estimated fair value	6	6
Liability, estimated fair value
Interest rate swaps
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount	240	240
Asset, estimated fair value	16	19
Liability, estimated fair value
Currency forwards
Gross Estimated Fair Values of Derivative Positions [Abstract]
Contractual/notional amount	13	12
Asset, estimated fair value
Liability, estimated fair value	$ (1)	$ (1)