Consolidated Statements of Earnings and Comprehensive Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Net premiums earned	$ 980,903	$ 865,747	$ 839,111
Net investment income	68,862	67,893	68,870
Net realized gains	64,222	17,885	17,520
Net unrealized gains on equity securities	65,258	32,101	78,090
Consolidated revenue	1,179,245	983,626	1,003,591
Losses and settlement expenses	456,602	442,884	413,416
Policy acquisition costs	317,468	286,438	288,697
Insurance operating expenses	76,907	66,828	69,430
Interest expense on debt	7,677	7,603	7,588
General corporate expenses	13,330	10,265	12,686
Total expenses	871,984	814,018	791,817
Equity in earnings of unconsolidated investees	37,060	20,233	20,960
Earnings before income taxes	344,321	189,841	232,734
Income tax expense:
Current	46,040	24,174	26,426
Deferred	18,927	8,576	14,666
Income tax expense	64,967	32,750	41,092
Net earnings	279,354	157,091	191,642
Other comprehensive earnings (loss), net of tax	(58,888)	56,219	67,045
Comprehensive earnings	$ 220,466	$ 213,310	$ 258,687
Basic net earnings per share	$ 6.18	$ 3.49	$ 4.28
Diluted net earnings per share	$ 6.11	$ 3.46	$ 4.23
Weighted average number of common shares outstanding:
Basic	45,230	45,000	44,734
Diluted	45,712	45,376	45,257