Property and equipment (Details) (USD $)			6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Building [Member]	Jun. 30, 2012 Machinery and Equipment [Member] Minimum [Member]	Jun. 30, 2012 Machinery and Equipment [Member] Maximum [Member]	Jun. 30, 2012 Furniture and Fixtures [Member]	Jun. 30, 2012 Leasehold Improvements [Member]
Property and equipment [Abstract]
Land	$ 10,680,000	$ 10,680,000
Building	24,505,574	24,505,574
Machinery and equipment	3,359,974	3,231,920
Furniture and fixtures	6,168,194	5,836,744
Leasehold Improvements	96,621	99,243
Property and equipment, gross	44,810,363	44,353,481
Accumulated depreciation	(8,351,571)	(7,639,903)
Total	$ 36,458,792	$ 36,713,578
Property, Plant and Equipment [Line Items]
Estimated useful life			39 years	3 years	7 years	7 years
Estimated useful life description							Shorter of estimated useful life or term of lease