Fair Value Measurements - Summary Fair Value of Outstanding Derivative Instruments (Detail) - Foreign currency forward contracts [Member] - USD ($)	Oct. 31, 2018	Jan. 31, 2018
Derivatives Fair Value [Line Items]
Notional amount of foreign currency derivative contracts	$ (9,931,000)	$ 36,266,000
Fair value of foreign currency derivative contracts	$ (9,849,000)	$ 36,531,000

Fair value of the assets less the liabilities of a derivative or group of derivatives.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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Balance Type:	debit
Period Type:	instant