Future Contract Benefits - Summary of Changes in Present Values of LFPB (Group Protection) (Details) - Group Protection - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024	Dec. 31, 2023
Present Value of Expected Future Policy Benefits
Balance as of beginning-of-year	$ 5,628	$ 5,689
Less: Effect of cumulative changes in discount rate assumptions			$ (550)	$ (490)
Beginning balance of original discount rate	6,178	6,179
Effect of actual variances from expected experience			$ (178)	$ (191)
Adjusted balance as of beginning-of-year	6,000	5,988
New incidence	808	838
Interest	100	93
Benefit payments	(724)	(757)
Ending balance at original discount rate	6,184	6,162
Effect of cumulative changes in discount rate assumptions	(425)	(593)
Balance as of end-of-period	5,759	5,569
Less: Reinsurance recoverables	3,439	4,284
Net balance as of end-of-period, net of reinsurance	$ 2,320	$ 1,285
Weighted-average duration of future policyholder benefit liability (years)	5 years	5 years