Net Loss Per Share - Summary of Weighted-Average Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities	337,250	2,576,252	337,250	2,576,252
Convertible preferred stock outstanding [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities		2,439,002		2,439,002
Warrants for convertible preferred stock [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities		14,000		14,000
Warrants for common stock [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities	106,000		106,000
Common stock options [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average anti-dilutive securities	231,250	123,250	231,250	123,250