Future Policy Benefits Reserves - Schedule of Balances and Changes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Present value of future net premiums
Balance, January 1					$ 3,993	$ 4,735
Effect of changes in discount rate	$ (67)	$ 40	$ (67)	$ 40	(74)	(880)
Balance, January 1, at original locked in discount rate					3,919	3,855
Effect of changes in cash flow assumptions					28	352
Expect of actual variances from expected experience					(112)	(40)
Adjusted balance, January 1	3,656	3,987	3,656	3,987	3,835	4,167
Interest accrual			153	161
Net premiums: earned during period			(332)	(341)
Balance, end of period at original locked in discount rate	3,656	3,987	3,656	3,987
Effect of changes in discount rate	(67)	40	(67)	40	(74)	(880)
Balance, September 30	3,589	4,027	3,589	4,027
Present value of future benefits & expenses
Balance, January 1					17,472	22,745
Effect of changes in discount rate	(873)	(134)	(873)	(134)	(125)	(5,942)
Balance, January 1, at original locked in discount rate			17,347	16,803
Effect of changes in cash flow assumptions					36	538
Effect of actual variances from expected experience					(45)	(21)
Adjusted balance, January 1					17,338	17,320
Interest accrual			723	730
Benefit & expense payments			(945)	(708)
Balance, end of period at original locked in discount rate	17,116	17,342	17,116	17,342
Effect of changes in discount rate	(873)	(134)	(873)	(134)	(125)	$ (5,942)
Balance, September 30	16,243	17,208	16,243	17,208
Net LFPB	12,654	13,181	12,654	13,181	$ 13,480		$ 19,132
Re-measurement loss of insurance claims and policyholders’ benefits	$ (41)	$ (211)	$ (75)	$ (205)