Segment Information - Financial Data by Segment (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Sales to unaffiliated customers	$ 19,535,000	$ 20,363,000	$ 27,594,000	$ 16,878,000	$ 15,836,000	$ 19,036,000	$ 24,029,000	$ 14,401,000	$ 84,369,770	$ 73,301,864
Operating income									5,360,520	4,284,964
Assets	67,827,816				55,221,736				67,827,816	55,221,736
Additions to property, plant and equipment									681,000	941,000
Depreciation and amortization									1,089,000	978,000
United States
Sales to unaffiliated customers									67,510,000	56,663,000
Operating income									4,394,000	3,485,000
Assets	56,115,000				43,174,000				56,115,000	43,174,000
Additions to property, plant and equipment									656,000	912,000
Depreciation and amortization									980,000	857,000
Canada
Sales to unaffiliated customers									8,808,000	8,514,000
Operating income									775,000	924,000
Assets	6,107,000				6,033,000				6,107,000	6,033,000
Additions to property, plant and equipment									14,000	26,000
Depreciation and amortization									36,000	36,000
Europe
Sales to unaffiliated customers									8,052,000	8,125,000
Operating income									192,000	(124,000)
Assets	5,606,000				6,015,000				5,606,000	6,015,000
Additions to property, plant and equipment									11,000	3,000
Depreciation and amortization									$ 73,000	$ 85,000