401(k) Plan - Additional Information (Details)	12 Months Ended
Jan. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Maximum allowed percentage of employee's pre-tax salary contributed to the 401(k) plan	100.00%
Defined contribution plan, plan name	401(k) Savings Plan

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration