Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 9,242	$ 7,995	$ 17,413	$ 14,985
Cost of goods sold, exclusive of depreciation and amortization	(6,926)	(5,850)	(13,402)	(11,288)
Selling, general and administrative	(1,312)	(1,343)	(3,077)	(2,919)
Interest expense	(14)	(10)	(35)	(19)
Arbitration award expense			(50)
Depreciation and amortization	(177)	(171)	(340)	(340)
Insurance proceeds - arbitration			4,500
Other income, net	128	11	130	12
Income (loss) before income tax provision (benefit)	941	632	5,139	431
Income tax provision (benefit)	320	185	1,747	129
Net income	621	447	3,392	302
Capital expenditures			647	877
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	9,242	7,995	17,413	14,985
Cost of goods sold, exclusive of depreciation and amortization	(6,926)	(5,850)	(13,402)	(11,288)
Selling, general and administrative	(1,312)	(1,343)	(3,077)	(2,919)
Interest expense	(14)	(10)	(35)	$ (19)
Arbitration award expense			(50)
Depreciation and amortization	(177)	(171)	(340)	$ (340)
Insurance proceeds - arbitration			4,500
Other income, net	128	11	130	$ 12
Income (loss) before income tax provision (benefit)	941	632	5,139	431
Income tax provision (benefit)	320	185	1,747	129
Net income	621	447	3,392	302
Capital expenditures	366	459	647	877
Operating Segments | ATG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	7,201	6,254	13,554	11,559
Cost of goods sold, exclusive of depreciation and amortization	(5,106)	(4,347)	(9,857)	(8,187)
Selling, general and administrative	(957)	(1,042)	(2,317)	(2,182)
Interest expense	(7)	(10)	(20)	$ (19)
Arbitration award expense			(50)
Depreciation and amortization	(124)	(123)	(241)	$ (245)
Insurance proceeds - arbitration			4,500
Other income, net	127	10	129	$ 10
Income (loss) before income tax provision (benefit)	1,134	742	5,698	936
Income tax provision (benefit)	385	226	1,937	280
Net income	749	516	3,761	656
Capital expenditures	187	81	375	453
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	2,041	1,741	3,859	3,426
Cost of goods sold, exclusive of depreciation and amortization	(1,820)	(1,503)	(3,545)	(3,101)
Selling, general and administrative	(355)	$ (301)	(760)	$ (737)
Interest expense	(7)		$ (15)
Arbitration award expense
Depreciation and amortization	(53)	$ (48)	$ (99)	$ (95)
Insurance proceeds - arbitration
Other income, net	1	1	$ 1	$ 2
Income (loss) before income tax provision (benefit)	(193)	(110)	(559)	(505)
Income tax provision (benefit)	(65)	(41)	(190)	(151)
Net income	(128)	(69)	(369)	(354)
Capital expenditures	$ 179	$ 378	$ 272	$ 424