Warrants Liability, at Fair Value - Summary of Company's Warrants Liability Activity (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Fair value, beginning of period				$ 1,819,562				$ 498,587	$ 1,819,562	$ 498,587	$ 1,645,240
Issuance of warrants									0	0	0
Exercise of warrants									(18,537)	(569,384)	(16,875)
Change in fair value	472,026	(906,787)	(223,591)	(335,514)	1,330,155	(2,676,601)	(498,587)	(45,326)	993,866	1,890,359	(1,129,778)
Fair value, end of period	$ 2,794,891				$ 1,819,562				$ 2,794,891	$ 1,819,562	$ 498,587