SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 709	$ 2,821	$ 3,193	$ 2,355	$ 695	$ 4,278	$ 3,125	$ 2,976	$ 9,078	$ 11,074	$ 13,860
Effect on cost of goods sold									172,889	163,662	176,256
Revenues	55,343	61,040	65,835	63,675	50,841	61,534	60,479	59,580	245,893	232,434	249,682
Gross margin	$ 16,728	$ 17,907	$ 19,864	$ 18,505	$ 14,346	$ 18,939	$ 17,987	$ 17,500	$ 73,004	$ 68,772	$ 73,426
Basic earnings per share (in dollars per share)	$ 0.08	$ 0.30	$ 0.34	$ 0.25	$ 0.08	$ 0.46	$ 0.34	$ 0.32	$ 1.01	$ 1.20	$ 1.52
Diluted earnings per share (in dollars per share)	$ 0.08	$ 0.30	$ 0.34	$ 0.25	$ 0.07	$ 0.46	$ 0.34	$ 0.32	$ 1.00	$ 1.20	$ 1.51
Scenario previously reported
Net income	$ 1,489	$ 2,520	$ 2,942	$ 2,127
Restatement Adjustment
Effect on cost of goods sold	$ 780	$ (301)	$ (251)	$ (228)