Future Contract Benefit - Summary of Gross Premiums and Interest Accretion (Group Protection) (Details) - Group Protection - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Liability for Future Policy Benefit, Activity [Line Items]
Gross premiums	$ 917	$ 887	$ 2,776	$ 2,676
Interest accretion	$ 48	$ 45	$ 148	$ 138