Property and Equipment (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Components of property and equipment
Property and equipment, gross	$ 98,745,102	$ 96,438,747
Less: accumulated depreciation	(27,578,120)	(25,843,609)
Property and equipment, net	71,166,982	70,595,138
Office equipment and furniture [Member]
Components of property and equipment
Property and equipment, useful life	5 years
Property and equipment, gross	161,009	156,810
Manufacturing equipment [Member]
Components of property and equipment
Property and equipment, gross	74,066,465	74,187,972
Manufacturing equipment [Member] | Minimum [Member]
Components of property and equipment
Property and equipment, useful life	5 years
Manufacturing equipment [Member] | Maximum [Member]
Components of property and equipment
Property and equipment, useful life	10 years
Vehicles [Member]
Components of property and equipment
Property and equipment, useful life	5 years
Property and equipment, gross	204,933	129,380
Construction in progress [Member]
Components of property and equipment
Property and equipment, useful life	0 years
Property and equipment, gross	2,531,687	477,299
Building and building improvements [Member]
Components of property and equipment
Property and equipment, useful life	20 years
Property and equipment, gross	$ 21,781,008	$ 21,487,286