Organization and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015	Feb. 01, 2016
Summary Of Significant Accounting Policies [Line Items]
Impairment of long-lived assets	$ 0
Goodwill impairment	0
Impairment losses on investment	$ 0
Expected dividend yield	0.00%	0.00%	0.00%
Accounting Standards Update (ASU) 2016-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment of changes recognized in beginning of retained earnings				$ 11,500,000
Cumulative effect adjustment of changes recognized in beginning of retained earnings as a result of adoption of new guidance for tax benefits that were not previously recognized [Member] | Accounting Standards Update (ASU) 2016-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment of changes recognized in beginning of retained earnings				11,700,000
Cumulative effect adjustment of changes recognized in beginning of retained earnings as a result of adoption of new guidance for accounting for forfeitures as they occur [Member] | Accounting Standards Update (ASU) 2016-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment of changes recognized in beginning of retained earnings				$ (200,000)