Investments - Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross investment income	$ 126,624	$ 91,543	$ 75,050
Less investment expenses	(6,241)	(5,465)	(6,188)
Net investment income	120,383	86,078	68,862
Fixed Income Securities
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross investment income	103,446	77,164	60,624
Equity Securities
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross investment income	12,238	11,912	11,787
Cash, Short-term Investments and Other Invested Assets
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross investment income	$ 10,940	$ 2,467	$ 2,639