CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Jan. 31, 2019	[1]	Jan. 31, 2018	[2]	Jan. 31, 2017	[2]
Income Statement [Abstract]
Revenue	$ 608,386		$ 506,142		$ 398,605
Cost of revenue	173,594		135,248		112,130
Gross profit	434,792		370,894		286,475
Operating expenses:
Research and development	163,750		136,791		115,928
Sales and marketing	312,210		303,319		253,020
General and administrative	93,069		84,805		68,182
Total operating expenses	569,029		524,915		437,130
Loss from operations	(134,237)		(154,021)		(150,655)
Interest expense, net	(316)		(1,013)		(896)
Other income, net	1,339		789		678
Loss before provision for income taxes	(133,214)		(154,245)		(150,873)
Provision for income taxes	1,398		715		914
Net loss	$ (134,612)		$ (154,960)		$ (151,787)
Net loss per share, basic and diluted	$ (0.95)	[3]	$ (1.16)		$ (1.19)
Weighted-average shares used to compute net loss per share, basic and diluted	141,351		133,932		127,469

[1] As reported under ASC Topic 606

[2] As reported under ASC Topic 605

[3] Due to rounding, numbers presented may not add up precisely to totals provided.