Segment Reporting Geographic Information (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]
Segment Reporting, Customer, Extent of Reliance, Description			10
Premiums Written, Gross	$ 163.4	$ 203.3	$ 344.2	$ 415.4
Final Audit Premium Accruals					$ 7.2	$ (13.0)
Surcharges and Assigned Risk Premiums					14.6	14.7
CALIFORNIA
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]
Premiums Written, Gross					$ 309.7	$ 355.8
Policies In force	43,641	46,685	43,641	46,685	43,641	46,685
FLORIDA
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]
Premiums Written, Gross					$ 53.7	$ 66.0
Policies In force	10,912	11,278	10,912	11,278	10,912	11,278
NEW YORK
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]
Premiums Written, Gross					$ 36.2	$ 37.6
Policies In force	7,793	7,878	7,793	7,878	7,793	7,878
AllOtherStates [Member]
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]
Premiums Written, Gross					$ 263.5	$ 311.8
Policies In force	65,255	68,580	65,255	68,580	65,255	68,580
UNITED STATES
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]
Premiums Written, Gross					$ 684.9	$ 772.9
Policies In force	127,601	134,421	127,601	134,421	127,601	134,421
Premiums Written, Gross excl. Adjustments					$ 663.1	$ 771.2