401(k) Plan - Additional Information (Details)	12 Months Ended
	Jan. 31, 2019 USD ($)
Compensation Related Costs [Abstract]
Maximum annual contributions per employee (as a percent)	85.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount	$ 4,000
Multiemployer Plan, Contributions by Employer	$ 1,400,000