Future Policy Benefits - Reconciliation of Net FPB to the Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits	$ 5,823	$ 5,021	$ 4,918
Traditional Life
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits	1,272	1,354	1,752
Immediate Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits	1,313	1,429	1,954
Deferred profit liability	82	69	57	$ 22
PRT
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits	3,152	2,165	1,148
Deferred profit liability	4	4	7	$ 0
Immediate annuities DPL
Liability for Future Policy Benefit, Activity [Line Items]
Deferred profit liability	82	69	57
PRT DPL
Liability for Future Policy Benefit, Activity [Line Items]
Deferred profit liability	$ 4	$ 4	$ 7