Basic and Diluted Net Loss Per Share - Potential Shares of Common Stock Excluded from Diluted Weighted-Average Common Shares Outstanding (Details) - shares	9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares excluded from diluted net loss per share	4,201,273	3,958,104
Employee stock purchase plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares excluded from diluted net loss per share	339,543	400,487
Options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares excluded from diluted net loss per share	1,796,127	2,189,301
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares excluded from diluted net loss per share	1,901,233	948,655
Common stock subject to repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares excluded from diluted net loss per share	66,439	255,706
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares excluded from diluted net loss per share	97,931	163,955