Reinsurance - Schedule of Assets in Support of Reserves (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	$ 94,200	$ 93,448
Derivative investments	8,337	9,945
Other investments	8,742	8,105
Cash and invested cash	7,345	9,502	$ 4,284	$ 5,801
Accrued investment income	1,170	1,122
Other assets	7,248	7,154
Fortitude Re
Ceded Credit Risk [Line Items]
Fixed maturity AFS securities	7,132	7,325
Derivative investments	13	21
Other investments	1,252	1,388
Cash and invested cash	42	88
Accrued investment income	87	88
Other assets	2	0
Total	$ 8,528	$ 8,910