CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Income Statement [Abstract]
Revenue	$ 155,944	$ 129,304	$ 444,673	$ 369,467
Cost of revenue	44,724	34,471	126,397	99,972
Gross profit	111,220	94,833	318,276	269,495
Operating expenses:
Research and development	42,310	34,812	122,388	102,388
Sales and marketing	84,490	81,670	238,472	225,604
General and administrative	23,884	20,910	69,959	63,037
Total operating expenses	150,684	137,392	430,819	391,029
Loss from operations	(39,464)	(42,559)	(112,543)	(121,534)
Interest expense, net	(47)	(287)	(208)	(802)
Other (loss) income, net	(321)	277	(1,243)	560
Loss before provision for income taxes	(39,832)	(42,569)	(113,994)	(121,776)
Provision for income taxes	364	355	924	519
Net loss	$ (40,196)	$ (42,924)	$ (114,918)	$ (122,295)
Net loss per common share, basic and diluted	$ (0.28)	$ (0.32)	$ (0.82)	$ (0.92)
Weighted-average shares used to compute net loss per share, basic and diluted	142,366	134,636	140,559	133,044