Segment Information (Schedule of Gross Premiums by Product) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Segment Reporting [Line Items]
Segment net premiums earned	$ 223,505	$ 236,275
Specialty P&C Segment
Segment Reporting [Line Items]
Segment net premiums earned	172,081	183,254
Specialty P&C Segment \| Operating segments
Segment Reporting [Line Items]
Ceded premiums earned	(17,582)	(17,672)
Segment net premiums earned	172,081	183,254
Specialty P&C Segment \| MPL \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	175,552	184,671
Specialty P&C Segment \| Medical Technology Liability \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	10,514	10,763
Specialty P&C Segment \| Lloyd's Syndicates \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	133	1,084
Specialty P&C Segment \| Other \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	3,464	4,408
Workers' Compensation Insurance Segment
Segment Reporting [Line Items]
Segment net premiums earned	40,665	41,524
Workers' Compensation Insurance Segment \| Operating segments
Segment Reporting [Line Items]
Ceded premiums earned	(16,305)	(16,452)
Segment net premiums earned	40,665	41,524
Workers' Compensation Insurance Segment \| Traditional business \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	43,894	43,627
Workers' Compensation Insurance Segment \| Alternative market business \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	13,076	14,349
Segregated Portfolio Cell Reinsurance Segment
Segment Reporting [Line Items]
Segment net premiums earned	10,759	11,497
Segregated Portfolio Cell Reinsurance Segment \| Operating segments
Segment Reporting [Line Items]
Ceded premiums earned	(1,731)	(1,846)
Segment net premiums earned	10,759	11,497
Segregated Portfolio Cell Reinsurance Segment \| MPL \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	715	649
Segregated Portfolio Cell Reinsurance Segment \| Workers' compensation \| Operating segments
Segment Reporting [Line Items]
Gross premiums earned:	$ 11,775	$ 12,694