Property, plant and equipment (Details) (USD $)			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Building and improvements [Member]	Mar. 31, 2013 Manufacturing and warehouse equipment [Member] Minimum [Member]	Mar. 31, 2013 Manufacturing and warehouse equipment [Member] Maximum [Member]	Mar. 31, 2013 Office equipment and furniture [Member] Minimum [Member]	Mar. 31, 2013 Office equipment and furniture [Member] Maximum [Member]	Mar. 31, 2013 Leasehold improvements [Member] Minimum [Member]	Mar. 31, 2013 Leasehold improvements [Member] Maximum [Member]	Mar. 31, 2013 Automobile [Member]
Summary of property, plant and equipment
Land	$ 278,325	$ 278,325
Building and improvements	4,492,197	4,489,377
Manufacturing and warehouse equipment	8,069,841	7,982,669
Office equipment and furniture	759,004	738,584
Construction in process	20,422	249,027
Leasehold improvements	328,015	122,644
Automobile	32,263
Property, plant and equipment, gross	13,980,067	13,860,626
Less accumulated depreciation	(8,706,353)	(8,532,717)
Property, plant and equipment, net	$ 5,273,714	$ 5,327,909
Estimated Useful Life			30 years	6 years	20 years	3 years	5 years	10 years	15 years	3 years