Shares of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2014
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible notes payable	0
Options to purchase common stock	2,417,918
Shares reserved for issuance	8,654,182
Warrants
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Shares reserved for issuance	1,164,648
2014 Stock Plan
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Shares reserved for issuance	689,529
Series A Convertible Preferred Stock [Member]
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible preferred stock	3,831,229
Series B Convertible Preferred Stock [Member]
Shares Of Common Stock Reserved For Future Issuance [Line Items]
Convertible preferred stock	550,858