Condensed Consolidated Statements of Earnings and Comprehensive Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Net premiums earned	$ 360,676	$ 307,723
Net investment income	32,847	27,084
Net realized gains	5,994	14,620
Net unrealized gains on equity securities	45,314	15,496
Consolidated revenue	444,831	364,923
Losses and settlement expenses	143,824	114,488
Policy acquisition costs	110,454	101,444
Insurance operating expenses	28,703	23,901
Interest expense on debt	1,618	2,008
General corporate expenses	5,010	4,214
Total expenses	289,609	246,055
Equity in earnings of unconsolidated investees	4,769	3,923
Earnings before income taxes	159,991	122,791
Income tax expense	32,091	23,980
Net earnings	127,900	98,811
Other comprehensive earnings (loss), net of tax	(12,671)	37,707
Comprehensive earnings	$ 115,229	$ 136,518
Basic net earnings per share	$ 2.80	$ 2.17
Diluted net earnings per share	$ 2.77	$ 2.15
Weighted average number of common shares outstanding:
Basic	45,684	45,530
Diluted	46,163	46,035