Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 279,181	$ 237,677
Less: accumulated depreciation	(155,204)	(120,501)
Total property and equipment, net	123,977	117,176
Servers and related equipment
Property Plant And Equipment [Line Items]
Total property and equipment, gross	170,422	143,219
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment, gross	72,599	64,379
Computer hardware and software
Property Plant And Equipment [Line Items]
Total property and equipment, gross	14,558	11,373
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, gross	14,254	12,824
Construction in progress
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 7,348	$ 5,882