Future Contract Benefits - Summary of Changes in Present Values of LFPB (Group Protection) (Details) - Group Protection - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Present Value of Expected LFPB
Balance as of beginning-of-year	$ 5,689	$ 5,462
Effect of cumulative changes in discount rate assumptions			$ (490)	$ (597)
Beginning balance at original discount rate	6,179	6,059
Effect of actual variances from expected experience			$ (191)	$ (220)
Adjusted balance as of beginning-of-year	5,988	5,839
Issuances	838	882
Interest accrual	93	83
Benefit payments	(757)	(734)
Ending balance at original discount rate	6,162	6,070
Effect of cumulative changes in discount rate assumptions	(592)	(577)
Balance as of end-of-period	5,570	5,493
Less: reinsurance recoverables	118	121
Net balance as of end-of-period, net of reinsurance	$ 5,452	$ 5,372
Weighted-average duration of future policyholder benefit liability	5 years	4 years