Insurance Contracts - Summarized Future Gross Undiscounted Premiums Expected to be Collected, and Future Expected Premiums Earned, Net of Reinsurance (Details) $ in Millions	Jun. 30, 2023 USD ($)
Future premiums expected to be collected, September 30, 2021	$ 7
Future premiums expected to be collected, December 31, 2021	5
Future premiums expected to be collected, December 31, 2022	27
Future premiums expected to be collected, December 31, 2023	26
Future premiums expected to be collected, December 31, 2024	25
Future premiums expected to be collected, December 31, 2025	24
Future premiums expected to be collected, December 31, 2030	100
Future premiums expected to be collected, December 31, 2035	63
Future premiums expected to be collected, December 31, 2040	29
Future premiums expected to be collected, December 31, 2045	14
Future premiums expected to be collected, December 31, 2050	4
Future premiums expected to be collected, December 31, 2055	0
Future premiums expected to be collected, Total	323
Future expected premiums to be earned, net of reinsurance, September 30, 2021	4
Future expected premiums to be earned, net of reinsurance, December 31, 2021	4
Future expected premiums to be earned, net of reinsurance, December 31, 2022	16
Future expected premiums to be earned, net of reinsurance, December 31, 2023	15
Future expected premiums to be earned, net of reinsurance, December 31, 2024	15
Future expected premiums to be earned, net of reinsurance, December 31, 2025	14
Future expected premiums to be earned, net of reinsurance, December 31, 2030	58
Future expected premiums to be earned, net of reinsurance, December 31, 2035	33
Future expected premiums to be earned, net of reinsurance, December 31, 2040	11
Future expected premiums to be earned, net of reinsurance, December 31, 2045	4
Future expected premiums to be earned, net of reinsurance, December 31, 2050	1
Future expected premiums to be earned, net of reinsurance, December 31, 2055	0
Future expected premiums to be earned, net of reinsurance, Total	$ 176