Related-Party Transactions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		33 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Jan. 31, 2017	Jan. 31, 2015	Jan. 31, 2013
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	$ 0.8	$ 0.5
License expenses included in research and development cost	0.7	0.4
Other Entity [Member] | Scenario, Forecast [Member]
Related Party Transaction [Line Items]
Commitment to make license payment			7.5
Investor [Member]
Related Party Transaction [Line Items]
Percentage of investor own voting stock					4.60%
Recognized revenue from related party	45.2	28.2
Account receivables from related party	$ 16.7			$ 12.1