Summary of Common Stock Reserved for Future Issuance (Detail)	Sep. 30, 2019 shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	10,905,850
Exercise of Outstanding Stock Options, Vesting of Restricted Stock Units ("RSU"), and Issuance of RSUs Vested but not Released
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	1,977,194
ESPP
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	293,888
Shares of Common Stock Available for Grant Under the 2011 Plan
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	473,319
Warrants to Purchase Common Stock
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	620,000
Shares of Common Stock Issuable Upon Conversion of Series B Preferred Stock
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	7,541,449