Future Contract Benefits - Summary of Gross Premiums and Interest Accretion (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Payout Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Gross premiums	$ 26	$ 40	$ 74	$ 84
Interest accretion	22	22	66	65
Traditional Life
Liability for Future Policy Benefit, Activity [Line Items]
Gross premiums	293	296	890	895
Interest accretion	$ 33	$ 34	$ 102	$ 101