Financial Instruments and Fair Value - Schedule of Cash Equivalents and Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2015	Jan. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable securities	$ 40,170	$ 40,130
Included in cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable securities	2,253	2,427
Included in marketable securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable securities	$ 37,917	$ 37,703