Consolidated Statements of Earnings and Comprehensive Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Net premiums earned	$ 1,614,346	$ 1,526,406	$ 1,294,306
Net investment income	159,739	142,278	120,383
Net realized gains	65,116	19,966	32,518
Net unrealized gains on equity securities	43,247	81,734	64,787
Consolidated revenue	1,882,448	1,770,384	1,511,994
Losses and settlement expenses	725,955	739,253	604,413
Policy acquisition costs	508,387	464,040	418,325
Insurance operating expenses	115,815	112,460	98,383
Interest expense on debt	5,358	6,331	7,301
General corporate expenses	17,028	15,880	15,917
Total expenses	1,372,543	1,337,964	1,144,339
Equity in earnings of unconsolidated investees	(3,924)	(4,869)	9,610
Earnings before income taxes	505,981	427,551	377,265
Income tax expense:
Current	90,017	71,720	64,944
Deferred	12,627	10,052	7,710
Income tax expense	102,644	81,772	72,654
Net earnings	403,337	345,779	304,611
Other comprehensive earnings (loss), net of tax	85,649	(7,420)	62,773
Comprehensive earnings	$ 488,986	$ 338,359	$ 367,384
Basic net earnings per share	$ 4.39	$ 3.78	$ 3.34
Diluted net earnings per share	$ 4.37	$ 3.74	$ 3.31
Weighted average number of common shares outstanding:
Basic	91,829	91,529	91,191
Diluted	92,391	92,451	92,155