Shares of Common Stock Reserved for Future Issuance (Detail)	Sep. 30, 2014
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible notes payable	1,508,162
Options to purchase common stock	2,267,918
Warrants	887,150
Shares reserved for issuance pursuant to 2014 Stock Plan	11,589,342
2014 Stock Plan
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Shares reserved for issuance pursuant to 2014 Stock Plan	1,000,311
Series A Convertible Preferred Stock [Member]
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible preferred stock	5,410,982
Series B Convertible Preferred Stock [Member]
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible preferred stock	514,819