Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 11,946	$ 9,616	$ 22,505	$ 18,719
Cost of goods sold, inclusive of depreciation and amortization	(9,022)	(7,830)	(17,531)	(15,074)
Selling, general and administrative	(2,013)	(1,622)	(3,641)	(3,462)
Interest expense	(27)	(15)	(52)	(38)
Income (loss) before income tax provision (benefits)	884	149	1,281	145
Income tax provision (benefits)	177	44	243	14
Net income (loss)	707	105	1,038	131
Capital expenditures			984	571
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	11,946	9,616	22,505	18,719
Cost of goods sold, inclusive of depreciation and amortization	(9,022)	(7,830)	(17,531)	(15,074)
Selling, general and administrative	(2,013)	(1,622)	(3,641)	(3,462)
Interest expense	(27)	(15)	(52)	(38)
Income (loss) before income tax provision (benefits)	884	149	1,281	145
Income tax provision (benefits)	177	44	243	14
Net income (loss)	707	105	1,038	131
Capital expenditures	473	388	984	571
Operating Segments | Advanced Technology Group ("ATG")
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	10,274	7,630	19,389	15,050
Cost of goods sold, inclusive of depreciation and amortization	(7,552)	(6,024)	(14,635)	(11,628)
Selling, general and administrative	(1,426)	(1,173)	(2,655)	(2,506)
Interest expense	(18)	(8)	(35)	(23)
Income (loss) before income tax provision (benefits)	1,278	425	2,064	893
Income tax provision (benefits)	262	127	392	239
Net income (loss)	1,016	298	1,672	654
Capital expenditures	440	314	845	495
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	1,672	1,986	3,116	3,669
Cost of goods sold, inclusive of depreciation and amortization	(1,470)	(1,806)	(2,896)	(3,446)
Selling, general and administrative	(587)	(449)	(986)	(956)
Interest expense	(9)	(7)	(17)	(15)
Income (loss) before income tax provision (benefits)	(394)	(276)	(783)	(748)
Income tax provision (benefits)	(85)	(83)	(149)	(225)
Net income (loss)	(309)	(193)	(634)	(523)
Capital expenditures	$ 33	$ 74	$ 139	$ 76