Reinsurance - Effects of Reinsurance on Net Written Premiums, Earned Premiums and Loss and Loss Settlement Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Written premiums:
Direct	$ 1,177,511	$ 1,061,358	$ 946,169
Assumed	217,904	159,335	137,786
Ceded	(163,945)	(153,792)	(99,732)
Net written premiums	1,231,470	1,066,901	984,223
Earned premiums:
Direct	1,109,903	1,017,917	941,998
Assumed	214,043	161,628	111,283
Ceded	(147,196)	(144,958)	(101,740)
Net earned premiums	1,176,750	1,034,587	951,541
Loss and loss settlement expenses:
Direct	641,410	763,609	655,775
Assumed	155,022	102,408	70,628
Ceded	(51,827)	(96,603)	(89,102)
Net loss and loss settlement expense	$ 744,605	$ 769,414	$ 637,301