Gold Lease Transaction - Additional Information (Detail)	3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Jan. 31, 2013 China Construction Bank USD ($)	Jan. 31, 2013 China Construction Bank CNY	Jul. 25, 2013 Shanghai Pudong Development Bank Ltd USD ($)	Jul. 25, 2013 Shanghai Pudong Development Bank Ltd CNY	Jan. 31, 2013 Shanghai Pudong Development Bank Ltd USD ($)	Jan. 31, 2013 Shanghai Pudong Development Bank Ltd CNY	Aug. 28, 2013 Wuhan Bank USD ($)	Aug. 28, 2013 Wuhan Bank CNY	Sep. 30, 2013 CITIC Bank USD ($)	Sep. 30, 2013 CITIC Bank CNY	Aug. 28, 2013 CITIC Bank USD ($)	Aug. 28, 2013 CITIC Bank CNY
Gold Lease Transactions [Line Items]
Line of credit facility, interest rate during period					6.00%	6.00%	6.00%	6.00%	6.00%	6.00%	5.60%	5.60%
Proceeds from secured lines of credit					$ 36,000,000	226,000,000	$ 4,400,000	26,800,000	$ 28,100,000	176,000,000	$ 6,700,000	41,600,000
Interest expense, debt	1,264,808	0	2,821,682	0
Line of credit facility, increase (decrease), net, total					65,400,000	400,000,000
Line of credit facility, increase (decrease), other, net						150,000,000
Line of credit facility, amount outstanding						250,000,000
Cash deposit							$ 391,000	2,400,000					$ 1,400,000	8,400,000	$ 1,400,000	8,400,000