Revenue Recognition - Cumulative Effects of Adjustments on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jul. 31, 2018	Feb. 01, 2018	Jan. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Deferred revenue, current	$ 583		$ 307
Retained earnings	244,425		$ 261,265
Topic 606 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Deferred revenue, current		$ 264
Retained earnings		261,308
Topic 606 [Member] | Adjustment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Deferred revenue, current	5,789	(43)
Retained earnings	$ (5,847)	$ 43