Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Income Statement [Abstract]
Revenue	$ 71,630	$ 65,142	$ 135,765	$ 122,299
Cost of revenue	26,825	21,672	49,997	42,122
Gross profit	44,805	43,470	85,768	80,177
Operating expenses:
Research and development	27,538	23,643	54,140	48,109
Selling, general and administrative	11,962	10,565	23,706	21,458
Total operating expenses	39,500	34,208	77,846	69,567
Income from operations	5,305	9,262	7,922	10,610
Other income	224	171	377	198
Income before income taxes	5,529	9,433	8,299	10,808
Provision for income taxes	2,226	801	2,432	393
Net income	$ 3,303	$ 8,632	$ 5,867	$ 10,415
Net income per share attributable to ordinary shareholders:
Basic	$ 0.10	$ 0.27	$ 0.18	$ 0.32
Diluted	$ 0.10	$ 0.25	$ 0.17	$ 0.31
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	33,227,717	32,557,398	33,240,767	32,492,723
Diluted	34,572,927	34,175,466	34,629,004	34,063,103