Other Current Assets (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Other Assets, Current [Line Items]
Supplies inventory	$ 803,371	$ 604,179
Deferred offering costs	326,630	341,166
Prepaid expenses	174,145	132,201
Other current assets	$ 1,304,146	$ 1,077,546