Employee Stock and Savings Plans - Stock Compensation Expense Recognized (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Stock-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 7,426	$ 5,709	$ 21,269	$ 17,162
Cost of goods sold
Stock-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	520	393	1,438	1,080
Research and development
Stock-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	2,865	2,272	8,018	6,604
Selling and marketing
Stock-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	1,998	1,644	5,651	4,818
General and administration
Stock-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 2,043	$ 1,400	$ 6,162	$ 4,660
Omnibus Incentive Plan
Stock-based Compensation, Allocation of Recognized Period Costs [Line Items]
Award requisite service period			4 years
Award expiry period from date of grant			10 years
Employee stock purchase plans
Stock-based Compensation, Allocation of Recognized Period Costs [Line Items]
Maximum number of shares that may be purchased by eligible participants (in shares)			6,000
Eligible employee stock purchase price			85.00%
Employee stock purchase plan offering term			6 months