Future Policy Benefit Reserves - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Insurance [Abstract]
Liability for future policy benefit, expected future gross premium, discounted, before reinsurance	$ 3,580		$ 3,580		$ 3,792
Liability for future policy benefit, weighted-average duration	11 years	11 years	11 years	11 years
Liability future policy benefit, losses recognized in current period	$ 65	$ 84	$ 93	$ 128
Liability future policy benefit, losses recognized in prior period	43	20	$ 54	$ 28
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease)	$ 7	$ 15