Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Income Statement [Abstract]
Revenue	$ 56,938	$ 64,135
Cost of revenue	22,046	23,172
Gross profit	34,892	40,963
Operating expenses:
Research and development	31,664	26,602
Selling, general and administrative	13,178	11,744
Total operating expenses	44,842	38,346
Income (loss) from operations	(9,950)	2,617
Other income, net	792	153
Income (loss) before income taxes	(9,158)	2,770
Provision for income taxes	848	206
Net income (loss)	$ (10,006)	$ 2,564
Net income (loss) per share attributable to ordinary shareholders:
Basic	$ (0.30)	$ 0.08
Diluted	$ (0.30)	$ 0.07
Weighted-average shares used to compute net income (loss) per share attributable to ordinary shareholders:
Basic	33,334,801	33,253,817
Diluted	33,334,801	34,685,081