Merger - Summary of Acquisition Date Fair Value of Consideration Transferred (Parenthetical) (Detail) - shares		3 Months Ended	12 Months Ended
	Jun. 15, 2015	May 31, 2014	Dec. 31, 2015	Dec. 31, 2016
Business Acquisition [Line Items]
Common stock outstanding			14,745,754	14,850,526
Ruthigen [Member]
Business Acquisition [Line Items]
Common stock outstanding	1,921,716
Common stock issued		136,000
Ruthigen [Member] | Private Placement [Member]
Business Acquisition [Line Items]
Common stock issued	379,387	379,387	379,387
Ruthigen [Member] | Employees [Member]
Business Acquisition [Line Items]
Common stock issued	36,000
Restricted Stock Units [Member]
Business Acquisition [Line Items]
Common stock outstanding			229,744	99,308
Restricted Stock Units [Member] | Ruthigen [Member]
Business Acquisition [Line Items]
Common stock issued	67,732