Subsequent Events (Details) - Subsequent event - USD ($) $ in Millions	Oct. 30, 2025	Oct. 27, 2025
Everest Group, Ltd. Renewal Rights
Subsequent Event [Line Items]
Consideration transferred for renewal rights		$ 301
Payments for reimbursable expenses for Everest		$ 30
Purchase price adjustment, percent of actual premiums written (as a percent)		15.00%
Reimbursable purchase price, percent of gross written premiums paid and payable less than aggregate premiums (as a percent)		80.00%
Reimbursable purchase price, maximum amount		$ 70
Transition services expense, per month amount		$ 10
Term of transition services payments		9 months
Forecast | Convex Group Limited
Subsequent Event [Line Items]
Equity ownership (as a percent)	35.00%
Consideration for equity method ownership	$ 2,100
Forecast | Onex Corporation
Subsequent Event [Line Items]
Equity ownership (as a percent)	9.90%
Consideration for equity method ownership	$ 646
Investment intent, amount	$ 2,000
Equity method investment period	3 years