Summary of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2015 shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	2,767,256
Warrant
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	741,047
Stock Options And Restricted Stock Units
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	1,503,722
Bluehill AG
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	10,355
Stock Incentive Plan Twenty Eleven
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	218,244
Employee Stock Purchase Plan
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Common stock reserved for future issuance	293,888