Derivative Instruments (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Derivative offsetting [Abstract]
Derivative assets subject to master netting agreements		$ 206	$ 197
Derivative liabilities subject to master netting agreements		115	119
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		$ 8	$ 59	$ (75)
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other assets	Other assets
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Other liabilities	Other liabilities
Not Designated as Hedging Instrument
Derivative [Line Items]
Asset derivatives - fair value		$ 206	$ 197
Liability derivatives - fair value		(115)	(119)
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		8	59	(75)
Not Designated as Hedging Instrument | Futures contracts
Derivative [Line Items]
Asset derivatives - fair value	[1]	78	139
Liability derivatives - fair value	[1]	(46)	(61)
Net derivatives - notional value	[2]	4,781	3,746
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		4	49	(86)
Not Designated as Hedging Instrument | Foreign currency forward contracts
Derivative [Line Items]
Asset derivatives - fair value	[1]	90	27
Liability derivatives - fair value	[1]	(48)	(32)
Net derivatives - notional value	[2]	1,698	1,224
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		(6)	21	6
Not Designated as Hedging Instrument | Other
Derivative [Line Items]
Asset derivatives - fair value	[1],[3]	38	31
Liability derivatives - fair value	[1],[3]	(21)	(26)
Net derivatives - notional value	[2],[3]	236	512
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments	[4]	$ 10	$ (11)	$ 5

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

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

[3] Includes swaps, options and other derivatives contracts

[4] Includes realized gains or losses on swaps, options and other derivatives contracts.