Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 10,559	$ 9,103
Cost of goods sold, exclusive of depreciation and amortization	(8,312)	(7,042)
Selling, general and administrative	(1,613)	(1,832)
Depreciation and amortization	(212)	(210)
Interest expense	(25)	(23)
Income (loss) before income tax provision (benefits)	397	(4)
Income tax provision (benefits)	66	(30)
Net income (loss)	331	26
Capital expenditures	511	183
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	10,559	9,103
Cost of goods sold, exclusive of depreciation and amortization	(8,312)	(7,042)
Selling, general and administrative	(1,613)	(1,832)
Depreciation and amortization	(212)	(210)
Interest expense	(25)	(23)
Income (loss) before income tax provision (benefits)	397	(4)
Income tax provision (benefits)	66	(30)
Net income (loss)	331	26
Capital expenditures	511	183
Operating Segments | Advanced Technology Group ("ATG")
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	9,115	7,420
Cost of goods sold, exclusive of depreciation and amortization	(6,947)	(5,464)
Selling, general and administrative	(1,216)	(1,327)
Depreciation and amortization	(149)	(146)
Interest expense	(17)	(15)
Income (loss) before income tax provision (benefits)	786	468
Income tax provision (benefits)	130	112
Net income (loss)	656	356
Capital expenditures	405	181
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	1,444	1,683
Cost of goods sold, exclusive of depreciation and amortization	(1,365)	(1,578)
Selling, general and administrative	(397)	(505)
Depreciation and amortization	(63)	(64)
Interest expense	(8)	(8)
Income (loss) before income tax provision (benefits)	(389)	(472)
Income tax provision (benefits)	(64)	(142)
Net income (loss)	(325)	(330)
Capital expenditures	$ 106	$ 2