Consolidated Statements Of Operations And Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
REVENUES:
Premiums earned	$ 2,656,403	$ 2,205,811	$ 7,602,640	$ 6,285,030
Net investment income	292,759	234,233	960,267	420,116
Net realized capital gains (losses):
Credit allowances on fixed maturity securities	(7,329)	6,196	(30,234)	(19,641)
Other net realized capital gains (losses)	3,107	104,007	169,023	103,904
Total net realized capital gains (losses)	(4,222)	110,203	138,789	84,263
Other income (expense)	(19,517)	59,937	44,190	47,306
Total revenues	2,925,423	2,610,184	8,745,886	6,836,715
CLAIMS AND EXPENSES:
Incurred losses and loss adjustment expenses	2,274,301	1,736,210	5,571,861	4,574,066
Commission, brokerage, taxes and fees	564,335	445,332	1,611,095	1,360,170
Other underwriting expenses	141,150	138,875	424,225	385,865
Corporate expenses	17,817	10,618	46,363	29,184
Interest, fees and bond issue cost amortization expense	15,539	6,641	46,785	21,477
Total claims and expenses	3,013,142	2,337,676	7,700,329	6,370,762
INCOME (LOSS) BEFORE TAXES	(87,719)	272,508	1,045,557	465,953
Income tax expense (benefit)	(14,251)	29,451	97,181	15,404
NET INCOME (LOSS)	(73,468)	243,057	948,376	450,549
Other comprehensive income (loss), net of tax:
Unrealized appreciation (depreciation) ("URA(D)") on securities arising during the period	(100,021)	63,480	(304,465)	335,835
Reclassification adjustment for realized losses (gains) included in net income (loss)	(1,388)	(11,453)	(3,464)	12,689
Total URA(D) on securities arising during the period	(101,409)	52,027	(307,929)	348,524
Foreign currency translation adjustments	(53,599)	60,628	(28,886)	30,390
Reclassification adjustment for amortization of net (gain) loss included in net income (loss)	1,563	1,806	5,649	4,532
Total benefit plan net gain (loss) for the period	1,563	1,806	5,649	4,532
Total other comprehensive income (loss), net of tax	(153,445)	114,461	(331,166)	383,446
COMPREHENSIVE INCOME (LOSS)	$ (226,913)	$ 357,518	$ 617,210	$ 833,995
EARNINGS PER COMMON SHARE:
Basic	$ (1.88)	$ 6.08	$ 23.74	$ 11.20
Diluted	$ (1.88)	$ 6.07	$ 23.72	$ 11.18