Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Sales	$ 356,858	$ 317,697	$ 261,644
Cost of sales	271,650	245,035	208,694
Gross profit	85,208	72,662	52,950
Operating expenses:
Salaries and commissions	38,110	36,570	29,369
Other operating expenses	30,962	28,716	24,714
Depreciation and amortization	2,178	2,772	3,018
Impairment charge	60		2,384
Total operating expenses	71,310	68,058	59,485
Operating income (loss)	13,898	4,604	(6,535)
Interest expense	2,907	2,073	845
Income (loss) before income taxes	10,991	2,531	(7,380)
Income tax expense (benefit)	2,355	2,753	(1,374)
Net income (loss)	$ 8,636	$ (222)	$ (6,006)
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.53	$ (0.01)	$ (0.37)
Diluted (in dollars per share)	$ 0.52	$ (0.01)	$ (0.37)
Weighted average common shares outstanding:
Basic (in shares)	16,389,876	16,269,611	16,345,679
Diluted (in shares)	16,523,599	16,269,611	16,345,679
Dividends declared per share (in dollars per share)			$ 0.15