Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Jan. 31, 2017	Jan. 31, 2016
Deferred tax assets:
Federal and state credits	$ 14,782	$ 11,852
Expenses not currently deductible	2,381	2,331
Stock-based compensation	3,561	2,503
Foreign deferred	161	0
Gross deferred tax assets	20,885	16,686
Valuation allowance	(15,061)	(12,072)
Total deferred tax assets	5,824	4,614
Deferred tax liabilities
Property and equipment	(1,383)	(1,378)
Foreign deferred	0	(33)
Net deferred tax assets	$ 4,441	$ 3,203