Consolidated Statements of Income (Loss) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Gross Written Premiums		$ 402,038	$ 374,930	$ 1,304,522	$ 1,201,372
Revenues:
Net Written Premiums		296,016	277,001	966,461	903,356
Change in Unearned Premiums		5,339	7,009	(85,140)	(86,996)
Net Earned Premiums		301,355	284,010	881,321	816,360
Net Investment Income		22,598	19,875	66,311	59,344
Total Other-Than-Temporary Impairment Losses		(957)	23	(2,005)	(248)
Portion of Loss Recognized in Other Comprehensive Income (Before Tax)		(15)	(23)	(60)	98
Net Other-Than-Temporary Impairment Losses Recognized in Earnings		(972)	0	(2,065)	(150)
Net Realized Gains		5,190	1,586	7,933	5,143
Other Income (Loss)		(1,699)	(183)	(1,042)	6,796
Total Revenues		326,472	305,288	952,458	887,493
Expenses:
Net Losses and Loss Adjustment Expenses		276,171	172,793	622,881	492,955
Commission Expenses		45,509	42,611	141,526	120,891
Other Operating Expenses		45,773	56,137	165,077	176,020
Interest Expense		3,862	3,859	11,584	11,575
Total Expenses		371,315	275,400	941,068	801,441
Income (Loss) Before Income Taxes		(44,843)	29,888	11,390	86,052
Income Tax Expense (Benefit)		(16,864)	7,875	(2,243)	24,917
Net Income (Loss)		$ (27,979)	$ 22,013	$ 13,633	$ 61,135
Net Income (Loss) per Common Share:
Basic	[1]	$ (0.95)	$ 0.76	$ 0.46	$ 2.10
Diluted	[1]	$ (0.95)	$ 0.73	$ 0.45	$ 2.04
Average common shares outstanding:
Basic	[1]	29,500	29,115	29,419	29,058
Diluted	[1]	29,500	30,141	30,006	29,997
Cash Dividends Declared per Common Share		$ 0.06	$ 0.045	$ 0.165	$ 0.09

[1] We completed a two-for-one stock split on January 20, 2017. All share and per share data prior to January 20, 2017 has been retroactively restated on a post-split basis.