Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Revenue from External Customer [Line Items]
Total revenue	$ 70,133	$ 54,645
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	44,587	34,460
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	18,637	14,028
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	3,018	2,253
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	2,690	2,673
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 1,201	$ 1,231