Balance Sheet Components - Additional Information (Details) - USD ($)	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Property Plant And Equipment [Line Items]
Accumulated depreciation of property and equipment acquired under capital lease	$ 10,400,000	$ 2,400,000
Depreciation expense	36,800,000	34,800,000	$ 25,400,000
Amount of interest capitalized to property and equipment	27,000	400,000	311,000
Servers and related equipment
Property Plant And Equipment [Line Items]
Gross amount of property and equipment acquired under capital lease	43,200,000	13,900,000
Depreciation expense	7,900,000	2,300,000	$ 140,000
Construction in progress
Property Plant And Equipment [Line Items]
Gross amount of property and equipment acquired under capital lease	$ 5,600,000	$ 1,200,000