Future Contract Benefits - Summary of Changes in Present Values of Expected Net Premiums and LFPB (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Present Value of Expected LFPB
Net balance as of end-of-period	$ 39,212		$ 40,174
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 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
Balance as of end-of-period	0	0
Present Value of Expected LFPB
Balance as of beginning-of-year	2,084	2,003
Effect of cumulative changes in discount rate assumptions	0	0
Beginning balance of original discount rate	2,271	2,266
Effect of actual variances from expected experience			1	(1)
Adjusted balance as of beginning-of-year	2,272	2,265
Issuances	15	27
Interest accrual	22	21
Benefit payments	(49)	(46)
Ending balance at original discount rate	2,260	2,267
Effect of cumulative changes in discount rate assumptions	(226)	(200)
Balance as of end-of-period	2,034	2,067
Net balance as of end-of-period	2,034	2,067	2,084
Less: reinsurance recoverables	1,572	10
Net balance as of end-of-period, net of reinsurance	$ 462	$ 2,057
Weighted-average duration of future policyholder benefit liability (years)	9 years	9 years
Deferred profit liability	$ 60	$ 43
Payout Annuities | Cumulative effect from adoption of new accounting standards
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	6,084	5,896
Beginning balance at original discount rate	6,236	6,480
Effect of actual variances from expected experience			23	(234)
Adjusted balance as of beginning-of-year			6,259	6,246
Issuances	109	177
Interest accrual	61	57
Net premiums collected	(199)	(195)
Flooring impact of LFPB	1	1
Ending balance at original discount rate	6,231	6,286
Balance as of end-of-period	5,974	6,051
Present Value of Expected LFPB
Balance as of beginning-of-year	9,637	9,086
Effect of cumulative changes in discount rate assumptions	(257)	(235)
Beginning balance of original discount rate	9,839	9,879
Effect of actual variances from expected experience			27	(243)
Adjusted balance as of beginning-of-year	9,866	9,636
Issuances	109	177
Interest accrual	94	89
Benefit payments	(191)	(169)
Ending balance at original discount rate	9,878	9,733
Effect of cumulative changes in discount rate assumptions	(386)	(316)
Balance as of end-of-period	9,492	9,417
Net balance as of end-of-period	3,518	3,366	3,553
Less: reinsurance recoverables	244	270
Net balance as of end-of-period, net of reinsurance	$ 3,274	$ 3,096
Weighted-average duration of future policyholder benefit liability (years)	10 years	11 years
Traditional Life | Cumulative effect from adoption of new accounting standards
Present Value of Expected Net Premiums
Balance as of beginning-of-year	$ (152)	$ (584)
Present Value of Expected LFPB
Balance as of beginning-of-year	(202)	(793)
Group Protection
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 of original discount rate	6,179	6,059
Effect of actual variances from expected experience			(67)	(100)
Adjusted balance as of beginning-of-year	6,112	5,959
Issuances	408	437
Interest accrual	48	42
Benefit payments	(382)	(377)
Ending balance at original discount rate	6,186	6,061
Effect of cumulative changes in discount rate assumptions	(546)	(569)
Balance as of end-of-period	5,640	5,492
Net balance as of end-of-period	5,640		5,689
Less: reinsurance recoverables	123	126
Net balance as of end-of-period, net of reinsurance	$ 5,517	$ 5,366
Weighted-average duration of future policyholder benefit liability (years)	5 years	4 years
UL and Other
Present Value of Expected LFPB
Balance as of beginning-of-year	$ 15,752	$ 14,777
Effect of cumulative changes in discount rate assumptions	(1,691)	(669)	(853)	(905)
Balance as of beginning-of-period, excluding shadow balance in AOCI	16,605	15,682
Effect of actual variances from expected experience			106	$ (9)
Adjusted balance as of beginning-of-year	16,711	15,673
Interest accrual	203	186
Net assessments collected	324	337
Benefit payments	(313)	(183)
Balance as of end-of-period, excluding shadow balance in AOCI	16,925	16,013
Balance as of end-of-period	15,234	15,344
Net balance as of end-of-period	15,234		$ 15,752
Less: reinsurance recoverables	9,734	2,007
Net balance as of end-of-period, net of reinsurance	$ 5,500	$ 13,337
Weighted-average duration of future policyholder benefit liability (years)	17 years	17 years