Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016	Jan. 31, 2017
Condensed Balance Sheet Statements Captions [Line Items]
Short-term investments	$ 7,926		$ 7,926		$ 0
Other than temporary impairment on investments			0
Depreciation and amortization	1,700	$ 2,500	3,605	$ 4,799
Sales Demonstration Equipment
Condensed Balance Sheet Statements Captions [Line Items]
Depreciation expense	$ 300	$ 900	$ 700	$ 1,700