Accounts Receivable (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 45,284,923	$ 31,082,460
Less: Allowance for doubtful debts	0	0
Accounts receivable, net	$ 45,284,923	$ 31,082,460