Policyholder Account Balances, Future Policy Benefits and Claims - Change in Unearned Income (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred Income [Roll Forward]
Beginning balance	$ 410	$ 333	$ 263
Deferral of revenue	84	104	92
Amortization	(25)	(27)	(22)
Ending balance	469	410	333
Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance	27	26	24
Deferral of revenue	1	2	3
Amortization	(1)	(1)	(1)
Ending balance	27	27	26
Variable Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance	150	112	86
Deferral of revenue	44	48	34
Amortization	(10)	(10)	(8)
Ending balance	184	150	112
Indexed Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance	233	195	153
Deferral of revenue	39	54	55
Amortization	(14)	(16)	(13)
Ending balance	$ 258	$ 233	195
Previously Reported
Deferred Income [Roll Forward]
Beginning balance			95
Previously Reported | Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance			19
Previously Reported | Variable Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance			76
Previously Reported | Indexed Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance			0
Effect of shadow reserve adjustments
Deferred Income [Roll Forward]
Beginning balance			168
Effect of shadow reserve adjustments | Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance			5
Effect of shadow reserve adjustments | Variable Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance			10
Effect of shadow reserve adjustments | Indexed Universal Life Insurance
Deferred Income [Roll Forward]
Beginning balance			$ 153