Segment, Geographic, and Product Line Information - Schedule of Revenues by Underwriting Division (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net written premiums	$ 149,875	$ 149,023	$ 471,241	$ 414,645
Operating Segments \| Underwriting Division \| Casualty
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net written premiums	91,997	95,287	311,492	277,626
Operating Segments \| Underwriting Division \| Professional Liability
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net written premiums	24,241	25,019	69,232	72,201
Operating Segments \| Underwriting Division \| Healthcare Liability
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net written premiums	23,208	24,127	62,112	55,651
Operating Segments \| Underwriting Division \| Baleen Specialty
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Net written premiums	$ 10,429	$ 4,590	$ 28,405	$ 9,167