Schedule II - Condensed Financial Information of Registrant (Parent Company) - Condensed Statements of Earnings and Comprehensive Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Statement Of Income Captions [Line Items]
Net investment income	$ 142,278	$ 120,383	$ 86,078
Net realized gains (losses)	19,966	32,518	588,515
Equity in earnings of unconsolidated investees	(4,869)	9,610	9,853
Interest expense on debt	(6,331)	(7,301)	(8,047)
Earnings before income taxes	427,551	377,265	720,678
Income tax expense	81,772	72,654	137,267
Net earnings	345,779	304,611	583,411
Unrealized gains (losses) on securities:
Other comprehensive earnings (loss)	(7,420)	62,773	(278,902)
Comprehensive earnings	338,359	367,384	304,509
Parent Company
Condensed Statement Of Income Captions [Line Items]
Net investment income	7,470	10,351	6,245
Net realized gains (losses)	(1,542)	14,134	570,888
Equity in earnings of unconsolidated investees			372
Selling, general and administrative expenses	(15,880)	(15,917)	(12,900)
Interest expense on debt	(3,617)	(6,543)	(7,622)
Earnings before income taxes	(13,569)	2,025	556,983
Income tax expense	(6,321)	(1,802)	108,699
Net earnings before equity in net earnings of subsidiaries	(7,248)	3,827	448,284
Equity in net earnings of subsidiaries	353,027	300,784	135,127
Net earnings	345,779	304,611	583,411
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during the period	(334)	1,754	(12,188)
Less: reclassification adjustment for (gains) losses included in net earnings	1,218		115
Other comprehensive earnings (loss) - parent only	884	1,754	(12,073)
Equity in other comprehensive earnings (loss) of subsidiaries/investees	(8,304)	61,019	(266,829)
Other comprehensive earnings (loss)	(7,420)	62,773	(278,902)
Comprehensive earnings	$ 338,359	$ 367,384	$ 304,509