Fair Value Measurements - Fair Value Hierarchy for Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Recurring Basis [Member] - Money Market Funds [Member] - USD ($) $ in Thousands	Apr. 30, 2017	Jan. 31, 2017
Assets:
Money market funds	$ 10,071	$ 10,058
Level 1 [Member]
Assets:
Money market funds	$ 10,071	$ 10,058