Description of Business and Summary of Significant Accounting Policies - Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Accounting Policies [Abstract]
Amortized deferred acquisition costs	$ 14.4	$ 10.0	$ 26.1	$ 17.5

Amount of amortization expense (reversal of expense) for deferred policy acquisition costs.

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