Segment Information - Schedule of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 1,023,019	$ 727,977	$ 440,333
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	762,391	561,352	343,625
Rest of the world
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 260,628	$ 166,625	$ 96,708