Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 91,043	$ 87,852	$ 87,892	$ 91,345	$ 85,005	$ 83,711	$ 82,174	$ 77,191	$ 358,132		$ 328,081		$ 345,887
Less: excise tax	2,850	1,519	2,139	4,176	3,860	3,820	1,782	356	10,684		9,818		18,283
Net sales	88,193	86,333	85,753	87,169	81,145	79,891	80,392	76,835	347,448		318,263		327,604
Cost of sales	68,668	67,708	66,928	68,128	63,560	64,770	64,861	59,789	271,432	[1]	252,980	[1]	269,071	[1]
Gross profit	19,525	18,625	18,825	19,041	17,585	15,121	15,531	17,046	76,016		65,283		58,533
SG&A expenses	8,993	8,154	8,311	7,649	6,987	6,981	6,404	6,321	33,107		26,693		25,683
Other operating income, net					0	(3,385)	0	0	0		(3,385)		0
Operating income	10,532	10,471	10,514	11,392	10,598	11,525	9,127	10,725	42,909		41,975		32,850
Gain (loss) on equity method investments	0	11,381	0	0					11,381		0		0
Equity method investment earnings	0	0	(819)	471	1,776	664	1,079	517	(348)		4,036		6,102
Interest expense	(250)	(224)	(379)	(331)	(314)	(341)	(328)	(311)	(1,184)		(1,294)		(534)
Income before income taxes	10,282	21,628	9,316	11,532	12,060	11,848	9,878	10,931	52,758		44,717		38,418
Income tax expense (benefit)	(2,357)	7,491	2,947	2,854	3,775	2,316	3,570	3,872	10,935		13,533		12,227
Net income	$ 12,639	$ 14,137	$ 6,369	$ 8,678	$ 8,285	$ 9,532	$ 6,308	$ 7,059	$ 41,823		$ 31,184		$ 26,191
Basic and diluted earnings per share data (in dollars per share)	$ 0.74	$ 0.82	$ 0.37	$ 0.50	$ 0.48	$ 0.55	$ 0.37	$ 0.41	$ 2.44		$ 1.82		$ 1.48
Dividends and dividend equivalents per common share and per unit (in dollars per share)	$ 0.04	$ 0.89	$ 0.04	$ 0.04	$ 0.02	$ 0.02	$ 0	$ 0.08

[1] Includes related party purchases of $18,425, and $29,596, $40,206 for the years ended December 31, 2017, 2016, and 2015, respectively.