Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Revenue from External Customer [Line Items]
Total revenue	$ 56,090	$ 67,922	$ 160,848	$ 171,520
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	35,073	42,986	96,846	101,567
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	14,642	18,011	43,635	49,745
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	1,970	2,264	6,856	9,848
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	2,433	2,804	8,449	6,688
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 1,972	$ 1,857	$ 5,062	$ 3,672