Outstanding Shares of Common Equivalent Shares Excluded from Computation of Diluted Net Income (Loss) per Share (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	4,226,170	3,787,915	4,226,170	3,787,915
Common stock warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	13,873	82,575	13,873	82,575