Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
REVENUES:
Net premiums written	$ 11,972,096	$ 10,954,467	$ 10,004,070
Change in net unearned premiums	(423,611)	(553,780)	(442,641)
Net premiums earned	11,548,485	10,400,687	9,561,429
Net investment income	1,333,161	1,052,835	779,185
Net investment gains:
Unrealized investment gains (losses), before tax	79,738	47,540	217,311
Change in allowance for expected credit losses on investments	37,970	(498)	(14,914)
Net investment gains (losses)	117,708	47,042	202,397
Revenues from non-insurance businesses	528,012	535,508	509,548
Insurance service fees	108,935	106,485	110,544
Other income	2,451	381	3,396
Total revenues	13,638,752	12,142,938	11,166,499
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	7,131,595	6,372,142	5,861,750
Other operating costs and expenses	3,602,306	3,363,936	2,961,505
Expenses from non-insurance businesses	513,451	524,998	493,189
Interest expense	126,907	127,459	130,374
Total operating costs and expenses	11,374,259	10,388,535	9,446,818
Pre-Tax Income (Loss)	2,264,493	1,754,403	1,719,681
Income tax expense	(509,916)	(370,557)	(334,727)
Net income before noncontrolling interests	1,754,577	1,383,846	1,384,954
Noncontrolling interests	1,538	(2,487)	(3,892)
Net income to common stockholders	$ 1,756,115	$ 1,381,359	$ 1,381,062
NET INCOME PER SHARE:
Basic (dollars per share)	$ 4.39	$ 3.40	$ 3.33
Diluted (dollars per share)	$ 4.36	$ 3.37	$ 3.29