Reinsurance - Schedule of Assets in Support of Reserves (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	$ 87,764	$ 88,738
Other investments	5,256	5,015
Cash and invested cash	4,122	3,365	$ 3,766	$ 3,343
Accrued investment income	1,127	1,082
Other assets	9,413	9,311
Fortitude Re
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	8,651	8,867
Other investments	1,002	759
Cash and invested cash	34	141
Accrued investment income	107	103
Other assets	5	1
Total	$ 9,799	$ 9,871