Stock-based Compensation - Classification of Stock-based Compensation (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Stock-based compensation:
Total stock-based compensation	$ 18,977	$ 17,308	$ 51,407	$ 49,968
Cost of revenue [Member]
Stock-based compensation:
Total stock-based compensation	368	335	981	922
Research and development [Member]
Stock-based compensation:
Total stock-based compensation	11,496	10,601	31,402	31,306
Selling, general and administrative [Member]
Stock-based compensation:
Total stock-based compensation	$ 7,113	$ 6,372	$ 19,024	$ 17,740

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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