Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	12 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Revenue from External Customer [Line Items]
Total revenue	$ 228,732	$ 227,768	$ 295,402
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	137,946	132,199	174,486
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	66,867	66,981	57,862
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	11,134	18,244	45,185
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	8,402	7,028	11,110
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 4,383	$ 3,316	$ 6,759

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