Short-Term Investments - Summary of Estimated Fair Value of Short-Term Investments, Designated as Available-for-Sale and Classified by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2013	Jan. 31, 2013
Amortized Cost And Fair Value Debt Securities [Abstract]
Due in one year	$ 13,514	$ 9,829
Due in greater than one year	2,728	4,447
Total	$ 16,242	$ 14,276