Accounts receivable, net (Schedule of Accounts Receivable) (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Accounts receivable, net [Abstract]
Accounts receivable	$ 25,408,181	$ 21,520,763
Less: allowance for doubtful debts	1,446,760	391,345
Accounts receivable, net	$ 23,961,421	$ 21,129,418