Accrued Liabilities - Schedule of Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Jan. 31, 2012
Accrued Liabilities [Line Items]
Accrued employee compensation	$ 8,599	$ 4,642
Refundable exercised unvested options	210	470
Accrued warranty	352	404
Accrued rebates	272	233
Accrued product development costs	2,875	679
Other accrued liabilities	2,111	1,503
Total accrued liabilities	$ 14,419	$ 7,931