Deferred Policy Acquisition Costs - ASU 2018-12 Transition Deferred Acquisition Costs Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Dec. 31, 2020
ASU 2018-12
Deferred policy acquisition costs	$ 1,101	$ 1,109	$ 1,013	$ 1,033	$ 1,046	$ 916
Accounting Standards Update 2018-12
ASU 2018-12
Deferred policy acquisition costs			1,013				$ 296
Effect of Modified Retrospective Application Accounting Standards Update 2018-12 | Accounting Standards Update 2018-12
ASU 2018-12
Deferred policy acquisition costs			(1)				33
As originally reported | Accounting Standards Update 2018-12
ASU 2018-12
Deferred policy acquisition costs			$ 1,014				$ 263