Consolidated Statements of Earnings and Comprehensive Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Net premiums earned	$ 1,294,306	$ 1,144,436	$ 980,903
Net investment income	120,383	86,078	68,862
Net realized gains	32,518	588,515	64,222
Net unrealized gains (losses) on equity securities	64,787	(121,037)	65,258
Consolidated revenue	1,511,994	1,697,992	1,179,245
Losses and settlement expenses	604,413	514,376	456,602
Policy acquisition costs	418,325	369,632	317,468
Insurance operating expenses	98,383	82,212	76,907
Interest expense on debt	7,301	8,047	7,677
General corporate expenses	15,917	12,900	13,330
Total expenses	1,144,339	987,167	871,984
Equity in earnings of unconsolidated investees	9,610	9,853	37,060
Earnings before income taxes	377,265	720,678	344,321
Income tax expense (benefit):
Current	64,944	186,906	46,040
Deferred	7,710	(49,639)	18,927
Income tax expense	72,654	137,267	64,967
Net earnings	304,611	583,411	279,354
Other comprehensive earnings (loss), net of tax	62,773	(278,902)	(58,888)
Comprehensive earnings	$ 367,384	$ 304,509	$ 220,466
Basic net earnings per share	$ 6.68	$ 12.86	$ 6.18
Diluted net earnings per share	$ 6.61	$ 12.74	$ 6.11
Weighted average number of common shares outstanding:
Basic	45,596	45,368	45,230
Diluted	46,077	45,794	45,712