Derivative Instruments (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative offsetting [Abstract]
Derivative assets subject to master netting agreements		$ 197	$ 147
Derivative liabilities subject to master netting agreements		119	73
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		59	(75)	$ (33)
Not Designated as Hedging Instrument
Derivative [Line Items]
Asset derivatives - fair value		197	149
Liability derivatives - fair value		(119)	(76)
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		59	(75)	(33)
Not Designated as Hedging Instrument | Futures contracts
Derivative [Line Items]
Net derivatives - notional value	[1]	3,746	3,138
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		49	(86)	(16)
Not Designated as Hedging Instrument | Futures contracts | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[2]	139	51
Not Designated as Hedging Instrument | Futures contracts | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[2]	(61)	(17)
Not Designated as Hedging Instrument | Foreign currency forward contracts
Derivative [Line Items]
Net derivatives - notional value	[1]	1,224	1,136
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		21	6	(40)
Not Designated as Hedging Instrument | Foreign currency forward contracts | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[2]	27	39
Not Designated as Hedging Instrument | Foreign currency forward contracts | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[2]	(32)	(35)
Not Designated as Hedging Instrument | Other
Derivative [Line Items]
Net derivatives - notional value	[1],[3]	512	3,592
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		(11)	5	$ 23
Not Designated as Hedging Instrument | Other | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[2],[3]	31	59
Not Designated as Hedging Instrument | Other | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[2],[3]	$ (26)	$ (24)

[1] Represents the absolute notional value of all outstanding contracts, consisting of long and short positions.

[2] The fair value of asset derivatives are included in ‘other assets’ and the fair value of liability derivatives are included in ‘other liabilities.’

[3] Includes swaps, options and other derivatives contracts