Investments - Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Investment income	$ 249,677	$ 219,339	$ 171,843
Investment expenses	(5,037)	(4,599)	(4,367)
Investment income, net of expenses	244,640	214,740	167,476
Total fixed income securities
Schedule of Investments [Line Items]
Investment income	230,524	202,655	166,306
Equity securities
Schedule of Investments [Line Items]
Investment income	624	529	437
Cash equivalents
Schedule of Investments [Line Items]
Investment income	18,498	16,111	5,049
Other
Schedule of Investments [Line Items]
Investment income	$ 31	$ 44	$ 51