Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Net premiums earned	$ 328,145	$ 276,011	$ 263,335
Net investment income	18,095	14,483	12,498
Commissions and other income	5,308	5,275	5,703
Net realized gains on investments, excluding impairment losses	19,835	28,971	6,439
Total other-than-temporary impairment losses on investments	(149)	(5,743)	(7,700)
Net realized gains (losses) on investments	19,686	23,228	(1,261)
Total revenues	371,234	318,997	280,275
Expenses:
Losses and loss expenses incurred	247,518	186,481	155,750
Other operating expenses	113,594	89,462	90,573
Total expenses	361,112	275,943	246,323
Income before federal income taxes (benefits)	10,122	43,054	33,952
Federal income taxes (benefits)	(8,201)	14,109	10,669
Net income	$ 18,323	$ 28,945	$ 23,283
Per share data:
Basic and diluted earnings (in dollars per share)	$ 1.21	$ 1.92	$ 1.55