Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
REVENUES:
Net premiums written	$ 10,954,467	$ 10,004,070	$ 8,862,867
Change in net unearned premiums	(553,780)	(442,641)	(756,836)
Net premiums earned	10,400,687	9,561,429	8,106,031
Net investment income	1,052,835	779,185	671,618
Net investment gains:
Unrealized investment gains (losses), before tax	47,540	217,311	106,958
Change in allowance for expected credit losses on investments	(498)	(14,914)	(16,326)
Net investment (losses) gains	47,042	202,397	90,632
Revenues from non-insurance businesses	535,508	509,548	489,151
Insurance service fees	106,485	110,544	93,857
Other income	381	3,396	4,177
Total revenues	12,142,938	11,166,499	9,455,466
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	6,372,142	5,861,750	4,953,960
Other operating costs and expenses	3,363,936	2,961,505	2,599,270
Expenses from non-insurance businesses	524,998	493,189	472,151
Interest expense	127,459	130,374	147,180
Total operating costs and expenses	10,388,535	9,446,818	8,172,561
Pre-Tax Income (Loss)	1,754,403	1,719,681	1,282,905
Income tax expense	(370,557)	(334,727)	(251,890)
Net income before noncontrolling interests	1,383,846	1,384,954	1,031,015
Noncontrolling interests	(2,487)	(3,892)	(8,525)
Net income to common stockholders	$ 1,381,359	$ 1,381,062	$ 1,022,490
NET INCOME PER SHARE:
Basic (dollars per share)	$ 5.10	$ 4.99	$ 3.69
Diluted (dollars per share)	$ 5.05	$ 4.94	$ 3.66