Reinsurance - Narrative (Details) - USD ($) $ in Billions	Mar. 31, 2026	Dec. 31, 2025
Effects of Reinsurance [Line Items]
Ceded reserves	$ 3.1
Reinsurance recoverables	$ 41.9	$ 40.7
Investment Grade
Effects of Reinsurance [Line Items]
Reinsurance recoverable (as a percent)	82.00%	80.00%
Non-Investment Grade
Effects of Reinsurance [Line Items]
Reinsurance recoverable (as a percent)	15.00%	17.00%
Non-Investment Grade | Captive Insurers
Effects of Reinsurance [Line Items]
Reinsurance recoverable (as a percent)	87.00%	87.00%
Not Rated
Effects of Reinsurance [Line Items]
Reinsurance recoverable (as a percent)	3.00%	3.00%