Segment Information - Schedule of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017		Oct. 31, 2018	Oct. 31, 2017
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 372,779	$ 277,591	[1]	$ 937,608	$ 684,906	[1]
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	263,488	192,919		678,166	505,045
Rest of the world
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 109,291	$ 84,672		$ 259,442	$ 179,861

[1] * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.