Stock Incentive Plans - Summary of Activity of Stock Incentive and Equity Plans (Detail)	9 Months Ended
	Sep. 30, 2016 $ / shares shares
Shares available for grant
Shares available for grant, Beginning balance	732,270
Shares available for grant, Authorized	1,900,000
Shares available for grant, Granted	(1,537,692)
Shares available for grant, Exercised/Issued	0
Shares available for grant, Cancelled/forfeited	1,031,098
Shares available for grant, Ending balance	2,125,676
Number of options outstanding
Number of options outstanding, Beginning balance	2,851,568
Number of options outstanding, Authorized	0
Number of options outstanding, Granted	943,620
Number of options outstanding, Exercised/Issued	0
Number of options outstanding, Cancelled/forfeited	(1,012,821)
Number of options outstanding, Ending balance	2,782,367
Weighted - average option exercise price
Weighted - average option exercise price, Beginning balance | $ / shares	$ 7.07
Weighted - average option exercise price, Authorized | $ / shares	0
Weighted - average option exercise price, Granted | $ / shares	0.63
Weighted - average option exercise price, Exercised/Issued | $ / shares	0
Weighted - average option exercise price, Cancelled/forfeited | $ / shares	9.61
Weighted - average option exercise price, Ending balance | $ / shares	$ 3.97
Number of restricted stock and board shares issued
Number of restricted stock and board shares issued, Beginning balance	201,455
Number of restricted stock and board shares issued, Authorized	0
Number of restricted stock and board shares issued, Granted	594,072
Number of restricted stock and board shares issued, Exercised/Issued	0
Number of restricted stock and board shares issued, Cancelled/forfeited	0
Number of restricted stock and board shares issued, Ending balance	795,527
Restricted Stock Units [Member]
Number of restricted stock units outstanding
Number of restricted stock units outstanding, Beginning balance	454,021
Number of restricted stock units outstanding, Authorized	0
Number of restricted stock units outstanding, Granted	0
Number of restricted stock units outstanding, Exercised/Issued	(3,702)
Number of restricted stock units outstanding, Cancelled/forfeited	(165,652)
Number of restricted stock units outstanding, Ending balance	284,667