Segment Information - Schedule of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 277,674	$ 196,956	$ 684,766	$ 500,117
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	192,977	152,134	504,937	385,464
Rest of the world
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 84,697	$ 44,822	$ 179,829	$ 114,653