Description of Business and Summary of Significant Accounting Policies - Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accounting Policies [Abstract]
Amortized deferred acquisition costs	$ 10.1	$ 8.2	$ 27.5	$ 31.3