Segment, Geographic, and Product Line Information - Revenues by Underwriting Division (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	$ 112,053	$ 76,432	$ 202,905	$ 140,389
Operating Segments | Underwriting Division | Casualty
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	76,350	44,472	138,789	81,939
Operating Segments | Underwriting Division | Professional Liability
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	24,432	24,542	38,805	38,040
Operating Segments | Underwriting Division | Healthcare
Revenues from External Customers and Long-Lived Assets [Line Items]
Net written premiums	$ 11,271	$ 7,418	$ 25,311	$ 20,410