Consolidated Statements Of Income (Loss) And Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
OPERATING REVENUES
Earned premiums	$ 1,099,862	$ 974,244	$ 3,116,038	$ 2,882,789
Net investment income	104,489	93,147	304,156	279,437
Other-than-temporary impairment losses	(3,444)	0	(7,261)	(12,080)
Net realized investment gains (losses), excluding other-than-temporary impairment losses	(36,563)	27,416	5,746	77,916
Net realized investment gains (losses)	(40,007)	27,416	(1,515)	65,836
Other revenues	341,804	336,475	980,713	955,339
Total Operating Revenues	1,506,148	1,431,282	4,399,392	4,183,401
OPERATING EXPENSES
Losses and loss adjustment expenses	1,075,432	579,405	2,210,129	1,564,925
Underwriting, acquisition and insurance expenses	395,909	372,521	1,169,175	1,112,789
Amortization of intangible assets	18,654	17,010	53,450	51,474
Other expenses	344,287	309,713	925,984	862,715
Total Operating Expenses	1,834,282	1,278,649	4,358,738	3,591,903
Operating Income (Loss)	(328,134)	152,633	40,654	591,498
Interest expense	31,814	33,152	97,013	97,690
Loss on early extinguishment of debt	0	0	0	44,100
Income (Loss) Before Income Taxes	(359,948)	119,481	(56,359)	449,708
Income tax expense (benefit)	(98,913)	36,060	(17,791)	121,968
Net Income (Loss)	(261,035)	83,421	(38,568)	327,740
Net income (loss) attributable to noncontrolling interests	(1,894)	(375)	1,044	4,777
Net Income (Loss) to Shareholders	(259,141)	83,796	(39,612)	322,963
OTHER COMPREHENSIVE INCOME
Net holding gains arising during the period	227,447	23,098	577,796	411,394
Change in unrealized other-than-temporary impairment losses on fixed maturities arising during the period	0	(17)	0	(40)
Reclassification adjustments for net gains included in net income (loss)	(5,207)	(9,758)	(14,598)	(33,308)
Change in net unrealized gains on investments, net of taxes	222,240	13,323	563,198	378,046
Change in foreign currency translation adjustments, net of taxes	16,263	(8,349)	19,770	(6,141)
Change in net actuarial pension loss, net of taxes	773	390	2,391	1,247
Total Other Comprehensive Income	239,276	5,364	585,359	373,152
Comprehensive Income (Loss)	(21,759)	88,785	546,791	700,892
Comprehensive income (loss) attributable to noncontrolling interests	(1,890)	(376)	1,064	4,795
Comprehensive Income (Loss) to Shareholders	$ (19,869)	$ 89,161	$ 545,727	$ 696,097
NET INCOME (LOSS) PER SHARE
Basic (in dollars per share)	$ (18.82)	$ 5.62	$ (4.52)	$ 22.27
Diluted (in dollars per share)	$ (18.82)	$ 5.60	$ (4.52)	$ 22.16