Consolidated Statements Of Income And Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
OPERATING REVENUES
Earned premiums	$ 1,033,574	$ 950,859	$ 2,016,176	$ 1,908,545
Net investment income	99,299	94,996	199,667	186,290
Other-than-temporary impairment losses	(604)	(3,675)	(3,817)	(12,080)
Net realized investment gains, excluding other-than-temporary impairment losses	18,231	20,916	42,309	50,500
Net realized investment gains	17,627	17,241	38,492	38,420
Other revenues	330,993	312,841	638,909	618,864
Total Operating Revenues	1,481,493	1,375,937	2,893,244	2,752,119
OPERATING EXPENSES
Losses and loss adjustment expenses	522,978	511,556	1,134,697	985,520
Underwriting, acquisition and insurance expenses	400,035	375,580	773,266	740,268
Amortization of intangible assets	18,026	17,204	34,796	34,464
Other expenses	299,112	277,909	581,697	553,002
Total Operating Expenses	1,240,151	1,182,249	2,524,456	2,313,254
Operating Income	241,342	193,688	368,788	438,865
Interest expense	31,797	33,697	65,199	64,538
Loss on early extinguishment of debt	0	44,100	0	44,100
Income Before Income Taxes	209,545	115,891	303,589	330,227
Income tax expense	58,118	35,218	81,122	85,908
Net Income	151,427	80,673	222,467	244,319
Net income attributable to noncontrolling interests	1,767	1,876	2,938	5,152
Net Income to Shareholders	149,660	78,797	219,529	239,167
OTHER COMPREHENSIVE INCOME
Net holding gains arising during the period	190,069	149,406	350,349	388,296
Change in unrealized other-than-temporary impairment losses on fixed maturities arising during the period	0	44	0	(23)
Reclassification adjustments for net gains included in net income	(222)	(10,567)	(9,391)	(23,550)
Change in net unrealized gains on investments, net of taxes	189,847	138,883	340,958	364,723
Change in foreign currency translation adjustments, net of taxes	1,962	(8,121)	3,507	2,208
Change in net actuarial pension loss, net of taxes	902	394	1,618	857
Total Other Comprehensive Income	192,711	131,156	346,083	367,788
Comprehensive Income	344,138	211,829	568,550	612,107
Comprehensive income attributable to noncontrolling interests	1,781	1,887	2,954	5,171
Comprehensive Income to Shareholders	$ 342,357	$ 209,942	$ 565,596	$ 606,936
NET INCOME PER SHARE
Basic (in dollars per share)	$ 10.34	$ 5.44	$ 14.25	$ 16.65
Diluted (in dollars per share)	$ 10.31	$ 5.41	$ 14.20	$ 16.55