Components of Inventory (Detail) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Schedule of Inventory [Line Items]
Finished goods	$ 556,841	$ 531,418
Work-in-process	230,127	210,459
Parts	2,945,707	2,739,335
Inventory, Gross, Total	3,732,675	3,481,212
Less: Inventory reserves	162,676	150,439
Total inventory, net	$ 3,569,999	$ 3,330,773