Stockholders' Equity (Detail)	Sep. 30, 2016 shares
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Options to purchase common stock	514,772
Shares reserved for issuance	7,488,964
Warrants
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Shares reserved for issuance	4,615,849
2014 Stock Plan
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Shares reserved for issuance	175,046
Series C Convertible Preferred Stock [Member]
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible preferred stock	500,668
Series D Convertible Preferred Stock [Member]
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible preferred stock	186,367
Series E Convertible Preferred Stock [Member]
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible preferred stock	1,496,262