Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Income Statement [Abstract]
Revenue	$ 47,188	$ 56,938
Cost of revenue	19,335	22,046
Gross profit	27,853	34,892
Operating expenses:
Research and development	33,017	31,664
Selling, general and administrative	13,077	13,178
Total operating expenses	46,094	44,842
Loss from operations	(18,241)	(9,950)
Other income, net	2,196	792
Loss before income taxes	(16,045)	(9,158)
Provision for income taxes	1,266	848
Net loss	$ (17,311)	$ (10,006)
Net loss per share attributable to ordinary shareholders:
Basic	$ (0.53)	$ (0.30)
Diluted	$ (0.53)	$ (0.30)
Weighted-average shares used to compute net loss per share attributable to ordinary shareholders:
Basic	32,492,044	33,334,801
Diluted	32,492,044	33,334,801