Consolidated Statements Of Operations And Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
REVENUES:
Premiums earned	$ 2,042,405	$ 1,817,299	$ 4,079,219	$ 3,549,996
Net investment income	38,083	179,028	185,883	320,004
Net realized capital gains (losses):
Credit allowances on fixed maturity securities	(4,063)		(25,837)
Other-than-temporary impairments on fixed maturity securities		(5,157)		8,090
Other net realized capital gains (losses)	188,711	35,429	(103)	130,594
Total net realized capital gains (losses)	184,648	30,272	(25,940)	122,504
Net derivative gain (loss)	11,869	353	(3,504)	3,584
Other income (expense)	(32,490)	(18,225)	(9,127)	(21,525)
Total revenues	2,244,515	2,008,727	4,226,531	3,974,563
CLAIMS AND EXPENSES:
Incurred losses and loss adjustment expenses	1,407,016	1,094,630	2,837,856	2,143,180
Commission, brokerage, taxes and fees	466,316	420,950	914,838	810,424
Other underwriting expenses	118,130	104,833	246,990	203,818
Corporate expenses	8,733	7,535	18,566	14,187
Interest, fees and bond issue cost amortization expense	7,253	8,434	14,836	16,065
Total claims and expenses	2,007,448	1,636,382	4,033,086	3,187,674
INCOME (LOSS) BEFORE TAXES	237,067	372,345	193,445	786,889
Income tax expense (benefit)	46,187	39,477	(14,047)	99,470
NET INCOME (LOSS)	190,880	332,868	207,492	687,419
Other comprehensive income (loss), net of tax :
Unrealized appreciation (depreciation) ("URA(D)") on securities arising during the period	551,753	197,759	272,354	430,824
Reclassification adjustment for realized losses (gains) included in net income (loss)	(7,257)	(1,869)	24,142	(3,691)
Total URA(D) on securities arising during the period	544,496	195,890	296,496	427,133
Foreign currency translation adjustments	20,586	(25,832)	(30,238)	(11,780)
Reclassification adjustment for amortization of net (gain) loss included in net income (loss)	1,806	1,151	2,726	2,302
Total benefit plan net gain (loss) for the period	1,806	1,151	2,726	2,302
Total other comprehensive income (loss), net of tax	566,888	171,209	268,984	417,655
COMPREHENSIVE INCOME (LOSS)	$ 757,768	$ 504,077	$ 476,476	$ 1,105,074
EARNINGS PER COMMON SHARE:
Basic	$ 4.78	$ 8.17	$ 5.14	$ 16.88
Diluted	$ 4.77	$ 8.15	$ 5.13	$ 16.82