Inventories by Major Categories (Detail) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Schedule of Inventory [Line Items]
Raw materials	$ 13,217,445	$ 12,906,713
Work in progress	630,848	419,695
Inventories	21,531,298	17,844,405
CCA and copper wire
Schedule of Inventory [Line Items]
Other inventory	3,313,426	2,947,584
Copper rod and anode
Schedule of Inventory [Line Items]
Other inventory	$ 4,369,579	$ 1,570,413