Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 9,465	$ 9,709	$ 28,708	$ 27,122
Cost of goods sold, exclusive of depreciation and amortization	(7,043)	(6,893)	(20,888)	(20,295)
Selling, general and administrative	(1,658)	(1,486)	(4,815)	(4,563)
Depreciation and amortization	(198)	(185)	(610)	(525)
Interest expense	(18)	(18)	(54)	(53)
Arbitration award expense				(50)
Insurance proceeds - arbitration				4,500
Other income, net	9	1	19	131
Income (loss) before income tax provision (benefit)	557	1,128	2,360	6,267
Income tax provision (benefit)	191	384	732	2,131
Net income (loss)	366	744	1,628	4,136
Capital expenditures			786	1,385
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	9,465	9,709	28,708	27,122
Cost of goods sold, exclusive of depreciation and amortization	(7,043)	(6,893)	(20,888)	(20,295)
Selling, general and administrative	(1,658)	(1,486)	(4,815)	(4,563)
Depreciation and amortization	(198)	(185)	(610)	(525)
Interest expense	(18)	(18)	(54)	(53)
Arbitration award expense				(50)
Insurance proceeds - arbitration				4,500
Other income, net	9	1	19	131
Income (loss) before income tax provision (benefit)	557	1,128	2,360	6,267
Income tax provision (benefit)	191	384	732	2,131
Net income (loss)	366	744	1,628	4,136
Capital expenditures	85	748	786	1,385
Operating Segments | ATG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	7,658	7,513	23,023	21,067
Cost of goods sold, exclusive of depreciation and amortization	(5,418)	(5,060)	(16,060)	(14,917)
Selling, general and administrative	(1,240)	(1,050)	(3,477)	(3,367)
Depreciation and amortization	(137)	(124)	(412)	(364)
Interest expense	(11)	(10)	(32)	(30)
Arbitration award expense				(50)
Insurance proceeds - arbitration				4,500
Other income, net	9	1	19	130
Income (loss) before income tax provision (benefit)	861	1,270	3,061	6,969
Income tax provision (benefit)	289	432	949	2,370
Net income (loss)	572	838	2,112	4,599
Capital expenditures	70	407	613	782
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	1,807	2,196	5,685	6,055
Cost of goods sold, exclusive of depreciation and amortization	(1,625)	(1,833)	(4,828)	(5,378)
Selling, general and administrative	(418)	(436)	(1,338)	(1,196)
Depreciation and amortization	(61)	(61)	(198)	(161)
Interest expense	(7)	(8)	(22)	(23)
Arbitration award expense
Insurance proceeds - arbitration
Other income, net				1
Income (loss) before income tax provision (benefit)	(304)	(142)	(701)	(702)
Income tax provision (benefit)	(98)	(48)	(217)	(239)
Net income (loss)	(206)	(94)	(484)	(463)
Capital expenditures	$ 15	$ 341	$ 173	$ 603