Related-Party Transactions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Related party [Member]
Related Party Transaction [Line Items]
Percentage of entity's voting stock owned by related party	10.00%	10.00%	10.00%
Other Entity [Member]
Related Party Transaction [Line Items]
Commitment to make license payment through January 2017	$ 7.5
Payment for license fees	2.3	1.7	1.8
License expenses commitments included in research and development cost	1.9	1.7	1.8
Investor [Member]
Related Party Transaction [Line Items]
Percentage of investor own voting stock			4.60%
Recognized revenue from related party	125.1	88.7	76.5
Account receivables from related party	$ 12.1	$ 7.9