Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 38,587	$ 36,729
Cost of goods sold, exclusive of depreciation and amortization	(28,564)	(27,641)
Selling, general and administrative	(6,668)	(6,162)
Depreciation and amortization	(823)	(718)
Interest expense	(73)	(70)
Arbitration award expense		(50)
Insurance proceeds - arbitration		4,500
Other income, net	11	140
Income (loss) before income tax provision (benefit)	2,470	6,728
Income tax provision (benefit)	717	2,131
Net income	1,753	4,597
Total assets	36,281	34,374
Capital expenditures	991	1,132
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	38,587	36,729
Cost of goods sold, exclusive of depreciation and amortization	(28,564)	(27,641)
Selling, general and administrative	(6,668)	(6,162)
Depreciation and amortization	(823)	(718)
Interest expense	(73)	(70)
Arbitration award expense		(50)
Insurance proceeds - arbitration		4,500
Other income, net	11	140
Income (loss) before income tax provision (benefit)	2,470	6,728
Income tax provision (benefit)	717	2,131
Net income	1,753	4,597
Total assets	36,281	34,374
Capital expenditures	991	1,132
Operating Segments | ATG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	31,059	28,596
Cost of goods sold, exclusive of depreciation and amortization	(21,919)	(20,390)
Selling, general and administrative	(4,808)	(4,492)
Depreciation and amortization	(559)	(493)
Interest expense	(43)	(40)
Arbitration award expense		(50)
Insurance proceeds - arbitration		4,500
Other income, net	11	139
Income (loss) before income tax provision (benefit)	3,741	7,770
Income tax provision (benefit)	1,086	2,462
Net income	2,655	5,308
Total assets	24,698	22,789
Capital expenditures	772	903
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	7,528	8,133
Cost of goods sold, exclusive of depreciation and amortization	(6,645)	(7,251)
Selling, general and administrative	(1,860)	(1,670)
Depreciation and amortization	(264)	(225)
Interest expense	(30)	(30)
Arbitration award expense
Insurance proceeds - arbitration
Other income, net		1
Income (loss) before income tax provision (benefit)	(1,271)	(1,042)
Income tax provision (benefit)	(369)	(331)
Net income	(902)	(711)
Total assets	11,583	11,585
Capital expenditures	$ 219	$ 229