Reconciliation of Provision For Income Taxes Determined at Local Income Tax Rate to Effective Income Tax Rate (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reconciliation of Effective Income Tax Rate [Line Items]
Pre-tax income	$ 18,628,552	$ 23,085,469	$ 57,887,722	$ 57,134,102
United States federal corporate income tax rate	34.00%	34.00%	34.00%	34.00%
Income tax computed at United States statutory corporate income tax rate	6,333,707	7,849,060	19,681,825	19,425,595
Loss not recognized as deferred tax assets	185,730	237,951	669,537	838,138
Non-deductible expenses	2,557	23,704	68,938	98,148
Change in fair value of warrants	10,200	(153,340)	20,903	(17,099)
Rate differential for PRC earnings	(1,729,302)	(2,103,517)	(5,395,230)	(5,370,521)
Other	(113,235)	4,973	(84,143)	11,525
Effective tax expense	$ 4,689,657	$ 5,858,831	$ 14,961,830	$ 14,985,786