Sales and Major Customers - Additional Information (Detail) - person	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Segment Reporting [Abstract]
Number of customers with revenue exceeding 10% of total Company revenue	2	2	0
Percentage change in total revenues by one customer	10.00%	10.00%	10.00%