Income Taxes (Details 3) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Jan. 31, 2012
Deferred tax assets:
Accruals and reserves	$ 1,760	$ 2,104
Deferred revenue	2,894	3,255
Stock-based compensation expense	1,892	1,549
U.S. federal, state and foreign tax credits	5,133	4,951
Net operating loss carryforwards	9,561	2,280
Property and equipment	116	0
Other	0	0
Deferred tax assets	21,356	14,139
Less: Valuation allowance	(19,250)	(10,544)
Net deferred tax assets	2,106	3,595
Deferred tax liabilities:
Intangible assets	4,336	5,594
Other	77	76
Property and equipment	0	362
Total net deferred tax assets(liabilities)	$ (2,307)	$ (2,437)