Segment Information - Financial Data by Segment (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Net sales	$ 26,377,000	$ 31,913,000	$ 40,997,000	$ 25,288,000	$ 23,118,000	$ 29,903,000	$ 33,954,000	$ 22,837,000	$ 124,574,371	$ 109,811,768
Operating income									8,442,056	7,347,006
Assets	92,066,092				81,421,366				92,066,092	81,421,366
Additions to property, plant and equipment									1,789,000	1,757,000
Depreciation and amortization									2,393,000	2,053,000
United States
Net sales									110,793,000	96,622,000
Operating income									7,769,000	7,147,000
Assets	84,104,000				73,688,000				84,104,000	73,688,000
Additions to property, plant and equipment									1,737,000	1,720,000
Depreciation and amortization									2,362,000	2,017,000
Canada
Net sales									6,824,000	6,804,000
Operating income									568,000	56,000
Assets	3,882,000				3,709,000				3,882,000	3,709,000
Additions to property, plant and equipment									7,000	19,000
Depreciation and amortization									8,000	8,000
Europe
Net sales									6,957,000	6,385,000
Operating income									105,000	144,000
Assets	$ 4,080,000				$ 4,024,000				4,080,000	4,024,000
Additions to property, plant and equipment									44,000	17,000
Depreciation and amortization									$ 23,000	$ 28,000