Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
REVENUES:
Net premiums written	$ 8,862,867	$ 7,262,437	$ 6,863,499
Change in net unearned premiums	(756,836)	(331,594)	(230,211)
Net premiums earned	8,106,031	6,930,843	6,633,288
Net investment income	671,618	583,821	645,614
Net investment gains:
Unrealized investment gains (losses), before tax	106,958	73,514	120,703
Change in allowance for expected credit losses on investments	(16,326)	29,486	0
Net investment gains	90,632	103,000	120,703
Revenues from non-insurance businesses	489,151	389,888	406,541
Insurance service fees	93,857	88,777	92,680
Other income	4,177	2,596	3,370
Total revenues	9,455,466	8,098,925	7,902,196
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	4,953,960	4,468,706	4,131,116
Other operating costs and expenses	2,599,270	2,390,392	2,362,082
Expenses from non-insurance businesses	472,151	384,488	402,669
Interest expense	147,180	150,537	153,409
Total operating costs and expenses	8,172,561	7,394,123	7,049,276
Pre-Tax Income (Loss)	1,282,905	704,802	852,920
Income tax expense	(251,890)	(171,817)	(168,935)
Net income before noncontrolling interests	1,031,015	532,985	683,985
Noncontrolling interests	(8,525)	(2,315)	(2,041)
Net income to common stockholders	$ 1,022,490	$ 530,670	$ 681,944
NET INCOME PER SHARE:
Basic (dollars per share)	$ 5.53	$ 2.84	$ 3.58
Diluted (dollars per share)	$ 5.48	$ 2.81	$ 3.52