Future Contract Benefits - Summary of Changes in Present Values of LFPB (Group Protection) (Details) - Group Protection - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Present Value of Expected LFPB
Balance as of beginning-of-year	$ 5,628	$ 5,689
Effect of cumulative changes in discount rate assumptions			$ (550)	$ (490)
Beginning balance at original discount rate	6,178	6,179
Effect of actual variances from expected experience			$ (72)	$ (67)
Adjusted balance as of beginning-of-year	6,106	6,112
Issuances	402	408
Interest accrual	50	48
Benefit payments	(371)	(382)
Ending balance at original discount rate	6,187	6,186
Effect of cumulative changes in discount rate assumptions	(475)	(546)
Balance as of end-of-period	5,712	5,640
Less: Reinsurance recoverables	121	123
Net balance as of end-of-period, net of reinsurance	$ 5,591	$ 5,517
Weighted-average duration of future policyholder benefit liability	5 years	5 years