Future Contract Benefits - Summary of Changes in Present Values of LFPB (UL and Other) (Details) - UL and Other - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Present Value of Expected LFPB
Balance as of beginning-of-year	$ 15,752	$ 14,777
Effect of cumulative changes in discount rate assumptions	(619)	(1,362)	$ (853)	$ (905)
Balance as of beginning-of-year, excluding shadow balance in AOCI	16,605	15,682
Effect of changes in cash flow assumptions			207	173
Effect of actual variances from expected experience			$ 170	$ (28)
Adjusted balance as of beginning-of-year	16,982	15,827
Interest accrual	623	573
Net assessments collected	946	334
Benefit payments	(718)	(473)
Balance as of end-of-year, excluding shadow balance in AOCI	17,833	16,261
Balance as of end-of-period	17,214	14,899
Less: reinsurance recoverables	10,499	1,897
Net balance as of end-of-period, net of reinsurance	$ 6,715	$ 13,002
Weighted-average duration of future policyholder benefit liability (years)	16 years	17 years