Future Contract Benefits - Summary of Changes in Present Values of Expected Net Premiums and LFPB (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Present Value of Expected LFPB
Net balance as of end-of-period	$ 41,169		$ 39,864
Payout Annuities
Present Value of Expected Net Premiums
Balance as of beginning-of-year	0	$ 0
Beginning balance at original discount rate	0	0
Effect of changes in cash flow assumptions			0	$ 0
Effect of actual variances from expected experience			0	0
Adjusted balance as of beginning-of-year	0	0
Issuances	0	0
Interest accrual	0	0
Net premiums collected	0	0
Flooring impact of LFPB	0	0
Ending balance at original discount rate	0	0
Effect of cumulative changes in discount rate assumptions	0	0
Balance as of end-of-period	0	0
Present Value of Expected LFPB
Balance as of beginning-of-year	2,085	2,004
Beginning balance at original discount rate	2,272	2,267
Effect of changes in cash flow assumptions			0	17
Effect of actual variances from expected experience			3	(1)
Adjusted balance as of beginning-of-year			2,275	2,283
Issuances	78	83
Interest accrual	65	64
Benefit payments	(152)	(143)
Ending balance at original discount rate	2,266	2,287
Effect of cumulative changes in discount rate assumptions	(147)	(344)
Balance as of end-of-period	2,119	1,943
Net balance as of end-of-period	2,119	1,943	2,085
Less: reinsurance recoverables	1,578	3
Net balance as of end-of-period, net of reinsurance	$ 541	$ 1,940
Weighted-average duration of future policyholder benefit liability	9 years	9 years
Deferred profit liability	$ 60	$ 38
Payout Annuities | Cumulative Effect, Period of Adoption, Adjustment
Present Value of Expected Net Premiums
Balance as of beginning-of-year	0	0
Present Value of Expected LFPB
Balance as of beginning-of-year	(187)	(263)
Traditional Life
Present Value of Expected Net Premiums
Balance as of beginning-of-year	6,200	6,063
Beginning balance at original discount rate	6,348	6,645
Effect of changes in cash flow assumptions			28	(12)
Effect of actual variances from expected experience			(59)	(280)
Adjusted balance as of beginning-of-year	6,317	6,353
Issuances	289	460
Interest accrual	188	182
Net premiums collected	(596)	(604)
Flooring impact of LFPB	1	(3)
Ending balance at original discount rate	6,199	6,388
Effect of cumulative changes in discount rate assumptions	(19)	(527)
Balance as of end-of-period	6,180	5,861
Present Value of Expected LFPB
Balance as of beginning-of-year	10,041	9,572
Beginning balance at original discount rate	10,230	10,357
Effect of changes in cash flow assumptions			(68)	(29)
Effect of actual variances from expected experience			(70)	(309)
Adjusted balance as of beginning-of-year			10,092	$ 10,019
Issuances	289	461
Interest accrual	299	288
Benefit payments	(576)	(537)
Ending balance at original discount rate	10,104	10,231
Effect of cumulative changes in discount rate assumptions	14	(832)
Balance as of end-of-period	10,118	9,399
Net balance as of end-of-period	3,938	3,538	$ 3,841
Less: reinsurance recoverables	388	450
Net balance as of end-of-period, net of reinsurance	$ 3,550	$ 3,088
Weighted-average duration of future policyholder benefit liability	9 years	9 years
Traditional Life | Cumulative Effect, Period of Adoption, Adjustment
Present Value of Expected Net Premiums
Balance as of beginning-of-year	$ (148)	$ (582)
Present Value of Expected LFPB
Balance as of beginning-of-year	$ (189)	$ (785)