Inventories by Major Categories (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Schedule of Inventory [Line Items]
Raw materials	$ 15,642,987	$ 12,906,713
Work in progress	618,107	419,695
Inventories	23,651,074	17,844,405
CCA and copper wire
Schedule of Inventory [Line Items]
Other inventory	3,289,058	2,947,584
Copper rod and anode
Schedule of Inventory [Line Items]
Other inventory	$ 4,100,922	$ 1,570,413