Reinsurance - Schedule of Assets in Support of Reserves (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	$ 88,297	$ 87,111
Derivative investments	7,849	9,677
Other investments	6,653	6,588
Cash and invested cash	4,284	5,801	$ 4,122	$ 3,365
Accrued investment income	1,134	1,108
Fortitude Re
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	7,549	7,764
Derivative investments	19	30
Other investments	1,465	1,419
Cash and invested cash	104	28
Accrued investment income	93	96
Total	$ 9,230	$ 9,337