Reinsurance - Schedule of Assets in Support of Reserves (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	$ 90,682	$ 88,738
Other investments	5,743	5,015
Cash and invested cash	6,013	3,365	$ 2,529	$ 3,343
Accrued investment income	1,160	1,082
Other assets	8,454	9,311
Fortitude Re
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	8,484	8,867
Other investments	1,178	759
Cash and invested cash	82	141
Accrued investment income	100	103
Other assets	0	1
Total	$ 9,844	$ 9,871