Short-Term Investments - Schedule of Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	$ 25,610	$ 14,271
Available-for-sale securities, Gross Unrealized Gains	16	7
Available-for-sale securities, Gross Unrealized Losses	(1)	(2)
Available-for-sale securities, Estimated Fair Value	25,625	14,276
Corporate notes and bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	10,499	11,474
Available-for-sale securities, Gross Unrealized Gains	9	7
Available-for-sale securities, Gross Unrealized Losses	(1)	(2)
Available-for-sale securities, Estimated Fair Value	10,507	11,479
U.S. agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	15,111
Available-for-sale securities, Gross Unrealized Gains	7
Available-for-sale securities, Estimated Fair Value	15,118
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost		2,097
Available-for-sale securities, Estimated Fair Value		2,097
Certificate of deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost		700
Available-for-sale securities, Estimated Fair Value		$ 700