Segment, Geographic, and Product Line Information - Schedule of Revenues by Underwriting Division (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 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	$ 181,025	$ 148,853	$ 321,367	$ 265,622
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	124,347	99,736	219,496	182,339
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	28,853	31,223	44,991	47,182
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	18,260	15,377	38,904	31,524
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	$ 9,565	$ 2,517	$ 17,976	$ 4,577