Segment Reporting - Schedule of Gross Premiums Written by Geographical Location of Subsidiaries (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]
Gross premiums written	$ 819,702	$ 698,845	$ 2,590,854	$ 2,254,177
Total International
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Gross premiums written	456,332	379,957	1,319,314	1,094,715
Lloyd’s of London
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Gross premiums written	278,288	234,252	800,328	674,235
Ireland
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Gross premiums written	126,543	103,610	377,617	302,070
U.S.
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Gross premiums written	51,501	42,095	141,369	118,410
Bermuda
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]
Gross premiums written	$ 363,370	$ 318,888	$ 1,271,540	$ 1,159,462