Consolidated Statements of Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Sales		$ 358,132	$ 328,081	$ 345,887
Less: excise taxes		10,684	9,818	18,283
Net sales		347,448	318,263	327,604
Cost of sales	[1]	271,432	252,980	269,071
Gross profit		76,016	65,283	58,533
Selling, general, and administrative (SG&A) expenses		33,107	26,693	25,683
Other operating income, net		0	(3,385)	0
Operating income		42,909	41,975	32,850
Gain on sale of equity method investment (Note 3)		11,381	0	0
Equity method investment earnings (loss) (Note 3)		(348)	4,036	6,102
Interest expense, net		(1,184)	(1,294)	(534)
Income before income taxes		52,758	44,717	38,418
Income tax expense (Note 6)		10,935	13,533	12,227
Net income		41,823	31,184	26,191
Income attributable to participating securities		996	954	873
Net income attributable to common shareholders and used in Earnings Per Share (EPS) calculation (Note 7)		$ 40,827	$ 30,230	$ 25,318
Share information
Basic and diluted weighted average common shares (in shares)		16,746,731	16,643,811	17,123,556
Basic and diluted earnings per share (in dollars per share)		$ 2.44	$ 1.82	$ 1.48
Dividends and dividend equivalents per common share (in dollars per share)		$ 1.01	$ 0.12	$ 0.06

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