Segment Information - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 428,409	$ 372,779	$ 1,151,436	$ 937,608
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	312,010	263,488	835,545	678,166
Rest of the world
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 116,399	$ 109,291	$ 315,891	$ 259,442