Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 10,296	$ 9,242	$ 19,243	$ 17,413
Cost of goods sold, exclusive of depreciation and amortization	(7,129)	(6,926)	(13,845)	(13,402)
Selling, general and administrative	(1,521)	(1,312)	(3,157)	(3,077)
Depreciation and amortization	(205)	(177)	(412)	(340)
Interest expense	(17)	(14)	(36)	(35)
Arbitration award expense				(50)
Insurance proceeds - arbitration				4,500
Other income, net	10	128	10	130
Income (loss) before income tax provision (benefit)	1,434	941	1,803	5,139
Income tax provision (benefit)	430	320	541	1,747
Net income (loss)	1,004	621	1,262	3,392
Capital expenditures			701	647
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	10,296	9,242	19,243	17,413
Cost of goods sold, exclusive of depreciation and amortization	(7,129)	(6,926)	(13,845)	(13,402)
Selling, general and administrative	(1,521)	(1,312)	(3,157)	(3,077)
Depreciation and amortization	(205)	(177)	(412)	(340)
Interest expense	(17)	(14)	(36)	(35)
Arbitration award expense				(50)
Insurance proceeds - arbitration				4,500
Other income, net	10	128	10	130
Income (loss) before income tax provision (benefit)	1,434	941	1,803	5,139
Income tax provision (benefit)	430	320	541	1,747
Net income (loss)	1,004	621	1,262	3,392
Capital expenditures	523	366	701	647
Operating Segments | ATG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	8,256	7,201	15,365	13,554
Cost of goods sold, exclusive of depreciation and amortization	(5,474)	(5,106)	(10,643)	(9,857)
Selling, general and administrative	(1,105)	(957)	(2,236)	(2,317)
Depreciation and amortization	(136)	(124)	(276)	(241)
Interest expense	(10)	(7)	(21)	(20)
Arbitration award expense				(50)
Insurance proceeds - arbitration				4,500
Other income, net	10	127	10	129
Income (loss) before income tax provision (benefit)	1,541	1,134	2,199	5,698
Income tax provision (benefit)	462	385	660	1,937
Net income (loss)	1,079	749	1,539	3,761
Capital expenditures	404	187	543	375
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	2,040	2,041	3,878	3,859
Cost of goods sold, exclusive of depreciation and amortization	(1,655)	(1,820)	(3,202)	(3,545)
Selling, general and administrative	(416)	(355)	(921)	(760)
Depreciation and amortization	(69)	(53)	(136)	(99)
Interest expense	(7)	(7)	(15)	(15)
Arbitration award expense
Insurance proceeds - arbitration
Other income, net		1		1
Income (loss) before income tax provision (benefit)	(107)	(193)	(396)	(559)
Income tax provision (benefit)	(32)	(65)	(119)	(190)
Net income (loss)	(75)	(128)	(277)	(369)
Capital expenditures	$ 119	$ 179	$ 158	$ 272