Basic and Diluted Net Loss Per Share - Outstanding Shares of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities (in shares)	46,100,125	31,819,339	46,100,125	31,819,339
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities (in shares)	13,200,266	10,252,607	13,200,266	10,252,607
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities (in shares)	1,403,888	1,525,736	1,403,888	1,525,736
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities (in shares)	750,000	1,250,000	750,000	1,250,000
Shares of common stock to be issued upon conversion of Series A Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities (in shares)	13,425,000	0	13,425,000	0
Shares of common stock to be issued upon conversion of convertible debt (Notes)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares of potentially dilutive securities (in shares)	17,320,971	18,790,996	17,320,971	18,790,996