Inventories (Detail) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Materials and parts	$ 4,760,273	$ 4,574,922
Work-in-process	281,424	0
Finished goods	912,426	1,171,429
Inventory, Gross, Total	5,954,123	5,746,351
Less: provision for obsolescence	(3,497,962)	(3,359,764)
Inventories, net	$ 2,456,161	$ 2,386,587