CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Income Statement [Abstract]
Revenue	$ 148,222	$ 122,941	$ 288,729	$ 240,163
Cost of revenue	42,605	32,778	81,673	65,501
Gross profit	105,617	90,163	207,056	174,662
Operating expenses:
Research and development	41,830	34,042	80,078	67,576
Sales and marketing	76,984	73,271	153,982	143,934
General and administrative	24,022	21,846	46,075	42,127
Total operating expenses	142,836	129,159	280,135	253,637
Loss from operations	(37,219)	(38,996)	(73,079)	(78,975)
Interest expense, net	(91)	(236)	(161)	(515)
Other (loss) income, net	(579)	267	(922)	283
Loss before provision for income taxes	(37,889)	(38,965)	(74,162)	(79,207)
Provision for income taxes	196	320	560	164
Net loss	$ (38,085)	$ (39,285)	$ (74,722)	$ (79,371)
Net loss per common share, basic and diluted	$ (0.27)	$ (0.30)	$ (0.54)	$ (0.60)
Weighted-average shares used to compute net loss per share, basic and diluted	140,718	132,981	139,639	132,237