Related-Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Related Party Transaction [Line Items]
Percentage of entity's voting stock owned by related party	10.00%
Other Entity [Member]
Related Party Transaction [Line Items]
Payment for license fees	$ 2.8	$ 2.8	$ 2.3
License expenses included in research and development expense	$ 2.9	$ 2.7	$ 1.9