Unpaid Loss and Loss Adjustment Expense - Activity in the Liability for Unpaid Loss and LAE (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Unpaid loss and LAE at beginning of period			$ 303.1	$ 298.1
Less: Reinsurance recoverable at beginning of period			133.8	149.5
Net unpaid loss and LAE at beginning of period			169.3	148.6
Add: Incurred loss and LAE, net of reinsurance, related to:
Current year			303.7	175.5
Prior years			(16.4)	(12.6)
Total incurred	$ 154.0	$ 77.5	287.3	162.9
Deduct: Paid loss and LAE, net of reinsurance, related to:
Current year			197.0	101.0
Prior years			68.7	54.5
Total paid			265.7	155.5
Unpaid loss and LAE, net of reinsurance recoverable, at end of period	190.9	156.0	190.9	156.0
Reinsurance recoverable at end of period	116.6	153.8	116.6	153.8
Unpaid loss and LAE, gross of reinsurance recoverable, at end of period	$ 307.5	$ 309.8	$ 307.5	$ 309.8