Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	3 Months Ended
Apr. 30, 2020	Apr. 30, 2019
Revenue from External Customer [Line Items]
Total revenue	$ 54,645	$ 47,188
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	34,460	27,600
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	14,028	14,488
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	2,253	3,483
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	2,673	883
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 1,231	$ 734

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration