Consolidated Statements Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
REVENUES:
Net premiums written	$ 2,050,038	$ 1,845,846
Change in net unearned premiums	(200,082)	(154,428)
Net premiums earned	1,849,956	1,691,418
Net investment income	158,577	174,763
Net realized and unrealized gains (losses) on investments	51,759	(143,285)
Change in allowance for expected credit losses on investments	(16,920)	(33,889)
Net investment gains (losses)	34,839	(177,174)
Revenues from non-insurance businesses	87,430	93,729
Insurance service fees	25,808	25,751
Other income	259	2,123
Total revenues	2,156,869	1,810,610
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	1,121,592	1,107,253
Other operating costs and expenses	616,268	578,334
Expenses from non-insurance businesses	86,290	94,757
Interest expense	36,651	36,734
Total operating costs and expenses	1,860,801	1,817,078
Income (loss) before income taxes	296,068	(6,468)
Income tax (expense) benefit	(64,352)	2,942
Net income (loss) before noncontrolling interests	231,716	(3,526)
Noncontrolling interests	(2,191)	(892)
Net income (loss) to common stockholders	$ 229,525	$ (4,418)
NET INCOME (LOSS) PER SHARE:
Basic (in dollar per share)	$ 1.24	$ (0.02)
Diluted (in dollar per share)	$ 1.23	$ (0.02)