Segment Information - Schedule of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018		Jan. 31, 2017
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 1,359,824	$ 1,024,762	[1]	$ 739,171	[1]
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	979,454	763,719		569,984
Rest of the world
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 380,370	$ 261,043		$ 169,187

[1] *As adjusted to reflect the impact of the full retrospective adoption of ASC 606 - see Note 2.