Future Contract Benefit (Summary of Changes in Present values of Expected Net Premiums and LFPB) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Present Value of Expected LFBP [Abstract]
Less: Effect of cumulative changes in discount rate assumptions	$ (905)	$ 1,113
Effect of changes in discount rate assumptions	(136)	(905)	$ 1,113
Liability for Future Policy Benefits, Total	37,860	38,302
Traditional Life [Member]
Present Value of Expected Net Premiums [Abstract]
Balance as of beginning-of-year	5,896	6,610
Less: Effect of cumulative changes in discount rate assumptions	(584)	843
Beginning balance of original discount rate	6,480	5,767
Effect of changes in cash flow assumptions	(5)	(382)
Effect of actual variances from expected experience	(262)	(21)
Adjusted beginning-of-year balance	6,213	5,364
Issuances	460	1,655
Interest accrual	176	209
Net premiums collected	(588)	(742)
Flooring impact of LFPB	3	(6)
Ending balance at original discount rate	6,264	6,480
Effect of cumulative changes in discount rate assumptions	(527)	(584)	843
Balance as of end-of-period	5,737	5,896
Present Value of Expected LFBP [Abstract]
Balance as of beginning-of-year	9,086	10,353
Less: Effect of cumulative changes in discount rate assumptions	(793)	1,460
Beginning balance of original discount rate	9,879	8,893
Effect of changes in cash flow assumptions		(21)	(321)
Effect of actual variances from expected experience	(289)	(5)
Adjusted balance as of beginning-of-year	9,569	8,567
Issuance	460	1,655
Interest Accrual	270	326
Benefit payments	(479)	(669)
Ending balance at original discount rate	9,820	9,879
Effect of changes in discount rate assumptions	(831)	(793)	1,460
Balance as of end-of-period	8,989	9,086
Liability for Future Policy Benefits, Total	3,252	3,190
Less: reinsurance recoverables	232	270
Net balance as of end-of-year, net of reinsurance	3,020	$ 2,920
Weighted-average duration of future policyholder benefit liability (years)		11 years
Payout Annuities [Member]
Present Value of Expected LFBP [Abstract]
Balance as of beginning-of-year	2,003	$ 2,511
Less: Effect of cumulative changes in discount rate assumptions	(263)	266
Beginning balance of original discount rate	2,266	2,245
Effect of changes in cash flow assumptions		17
Effect of actual variances from expected experience	(1)	3
Adjusted balance as of beginning-of-year	2,282	2,248
Issuance	83	122
Interest Accrual	64	84
Benefit payments	(142)	(188)
Ending balance at original discount rate	2,287	2,266
Effect of changes in discount rate assumptions	(344)	(263)	266
Balance as of end-of-period	1,943	2,003
Liability for Future Policy Benefits, Total	1,943	2,003
Less: reinsurance recoverables	11	10
Net balance as of end-of-year, net of reinsurance	1,932	$ 1,993
Weighted-average duration of future policyholder benefit liability (years)		9 years
Deferred Profit Liability	38	$ 38	22
Group Protection [Member]
Present Value of Expected LFBP [Abstract]
Balance as of beginning-of-year	5,462	5,936
Less: Effect of cumulative changes in discount rate assumptions	(597)	262
Beginning balance of original discount rate	6,059	5,674
Effect of changes in cash flow assumptions	(27)	15
Effect of actual variances from expected experience	(233)	(117)
Adjusted balance as of beginning-of-year	5,799	5,572
Issuance	1,267	1,777
Interest Accrual	122	141
Benefit payments	(1,095)	(1,431)
Ending balance at original discount rate	6,093	6,059
Effect of changes in discount rate assumptions	(720)	(597)	262
Balance as of end-of-period	5,373	5,462
Less: reinsurance recoverables	117	127
Net balance as of end-of-year, net of reinsurance	$ 5,256	$ 5,335
Weighted-average duration of future policyholder benefit liability (years)	5 years	4 years
UL and Other [Member]
Present Value of Expected LFBP [Abstract]
Balance as of beginning-of-year	$ 14,777	$ 12,513
Balance as of beginning-of-year, excluding shadow balance in AOCI	15,682	11,400
Effect of changes in cash flow assumptions		173	3,108
Effect of actual variances from expected experience		(28)	$ 195
Adjusted balance as of beginning-of-year	15,827	14,703
Issuance		7
Interest Accrual	573	626
Net assessments collected	334	974
Benefit payments	(473)	(628)
Balance as of end-of-period, excluding shadow balance in AOCI	16,261	15,682
Balance as of end-of-period	14,899	14,777
Less: reinsurance recoverables	1,897	1,975
Net balance as of end-of-year, net of reinsurance	$ 13,002	$ 12,802
Weighted-average duration of future policyholder benefit liability (years)	17 years	17 years