Undiscounted and Discounted Future Benefit Payments and Gross Premiums (Details) - Life policy reserves: - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Term Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	$ 4,768			$ 4,618
Undiscounted expected future gross premiums	4,364			4,402
Discounted expected future benefit payments	2,521	$ 2,662	$ 2,584	2,520	$ 2,702	$ 2,993
Discounted expected future gross premiums	2,464			2,528
Whole Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Undiscounted expected future benefit payments	1,631			1,540
Undiscounted expected future gross premiums	653			596
Discounted expected future benefit payments	586	$ 633	$ 614	594	$ 646	$ 826
Discounted expected future gross premiums	$ 379			$ 356