Segment, Geographic, and Product Line Information - Schedule of Revenues by Underwriting Division (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	$ 558,187	$ 451,422	$ 334,672
Underwriting Division | Casualty
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	366,302	292,905	192,062
Underwriting Division | Professional Liability
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	98,817	90,266	87,588
Underwriting Division | Healthcare Liability
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	77,173	67,029	55,022
Underwriting Division | Baleen Specialty
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	15,895	1,222
Operating Segments | Underwriting Division | Casualty
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	366,302	292,905	192,062
Operating Segments | Underwriting Division | Professional Liability
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	98,817	90,266	87,588
Operating Segments | Underwriting Division | Healthcare Liability
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	77,173	67,029	55,022
Operating Segments | Underwriting Division | Baleen Specialty
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	$ 15,895	$ 1,222	$ 0