Long-term loans (Details)			3 Months Ended	9 Months Ended
	Sep. 30, 2012 USD ($)	Dec. 31, 2011 USD ($)	Sep. 30, 2012 Bank Of China [Member] USD ($)	Sep. 30, 2012 Bank Of China [Member] USD ($)	Sep. 30, 2012 Bank Of China [Member] CNY	Dec. 31, 2011 Bank Of China [Member] USD ($)
Debt Instrument [Line Items]
Long term loan term				5 years
Long-term loans, face amount			$ 7,954,437	$ 7,954,437	50,000,000
Long term loans from Bank of China			7,954,437	7,954,437
Less: current portion of long-term borrowings	1,749,976		1,749,976	1,749,976
Long-term borrowings, net of current portion	6,204,461		6,204,461	6,204,461
Interest rate multiple			110.00%	110.00%
Minimum interest rate				7.04%
Maximum interest rate				7.59%
Interest on long-term loans			149,637	318,424
Percent of principle to be paid in current year				2.00%
Percent of principle to be paid in subsequent periods				6.00%
Repayment schedule of the principal
Within 1 year			1,749,976	1,749,976
2 to 3 years			1,909,065	1,909,065
3 to 4 years			1,909,065	1,909,065
4 to 5 years			1,909,065	1,909,065
5 to 6 years			477,266	477,266
Principal payment				$ 159,089