Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Jan. 31, 2017	Jan. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 10,347	$ 9,832
Business credit carryforwards	9,593	7,685
Accrued expenses	1,155	1,129
Amortization	221	179
Stock-based compensation	1,048	824
Deferred revenue		253
Deferred rent	1,041	946
Unrealized foreign exchange losses	11	151
Gross deferred tax assets	23,416	20,999
Valuation allowance	(21,929)	(19,962)
Total deferred tax assets	1,487	1,037
Deferred tax liabilities:
Depreciation	(873)	(785)
Deferred revenue	(272)
Total deferred tax liabilities	(1,145)	(785)
Net deferred tax assets	$ 342	$ 252