Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 9,709	$ 8,031	$ 27,122	$ 23,016
Cost of goods sold, exclusive of depreciation and amortization	(6,893)	(6,125)	(20,295)	(17,413)
Selling, general and administrative	(1,486)	(1,262)	(4,563)	(4,181)
Interest expense	(18)	(12)	(53)	(31)
Arbitration award expense		(5,419)	(50)	(5,419)
Depreciation and amortization	(185)	(150)	(525)	(490)
Insurance proceeds - arbitration			4,500
Other income, net	1	4	131	16
Income (loss) before income tax provision (benefit)	1,128	(4,933)	6,267	(4,502)
Income tax provision (benefit)	384	(1,632)	2,131	(1,503)
Net income	744	(3,301)	4,136	(2,999)
Capital expenditures			1,395	1,777
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	9,709	8,031	27,122	23,016
Cost of goods sold, exclusive of depreciation and amortization	(6,893)	(6,125)	(20,295)	(17,413)
Selling, general and administrative	(1,486)	(1,262)	(4,563)	(4,181)
Interest expense	$ (18)	(12)	(53)	(31)
Arbitration award expense		(5,419)	(50)	(5,419)
Depreciation and amortization	$ (185)	(150)	(525)	$ (490)
Insurance proceeds - arbitration			4,500
Other income, net	1	4	131	$ 16
Income (loss) before income tax provision (benefit)	1,128	(4,933)	6,267	(4,502)
Income tax provision (benefit)	384	(1,632)	2,131	(1,503)
Net income	744	(3,301)	4,136	(2,999)
Capital expenditures	748	900	1,395	1,777
Operating Segments | ATG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	7,513	6,443	21,067	18,002
Cost of goods sold, exclusive of depreciation and amortization	(5,060)	(4,471)	(14,917)	(12,658)
Selling, general and administrative	(1,050)	(914)	(3,367)	(3,096)
Interest expense	$ (10)	(12)	(30)	(31)
Arbitration award expense		(5,419)	(50)	(5,419)
Depreciation and amortization	$ (124)	(106)	(364)	$ (351)
Insurance proceeds - arbitration			4,500
Other income, net	1	3	130	$ 13
Income (loss) before income tax provision (benefit)	1,270	(4,476)	6,969	(3,540)
Income tax provision (benefit)	432	(1,462)	2,370	(1,183)
Net income	838	(3,014)	4,599	(2,357)
Capital expenditures	407	149	782	602
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	2,196	1,588	6,055	5,014
Cost of goods sold, exclusive of depreciation and amortization	(1,833)	(1,654)	(5,378)	(4,755)
Selling, general and administrative	(436)	$ (348)	(1,196)	$ (1,085)
Interest expense	$ (8)		$ (23)
Arbitration award expense
Depreciation and amortization	$ (61)	$ (44)	$ (161)	$ (139)
Insurance proceeds - arbitration
Other income, net		1	$ 1	$ 3
Income (loss) before income tax provision (benefit)	$ (142)	(457)	(702)	(962)
Income tax provision (benefit)	(48)	(170)	(239)	(320)
Net income	(94)	(287)	(463)	(642)
Capital expenditures	$ 341	$ 751	$ 613	$ 1,175