Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Income Statement [Abstract]
Revenue	$ 57,157	$ 71,013
Cost of revenue	20,450	25,095
Gross profit	36,707	45,918
Operating expenses:
Research and development	24,466	16,583
Selling, general and administrative	10,893	9,010
Total operating expenses	35,359	25,593
Income from operations	1,348	20,325
Other income	27	27
Income before income taxes	1,375	20,352
Provision (benefit) for income taxes	(408)	1,498
Net income	$ 1,783	$ 18,854
Net income per share attributable to ordinary shareholders:
Basic	$ 0.05	$ 0.61
Diluted	$ 0.05	$ 0.56
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	32,428,047	31,099,081
Diluted	33,950,736	33,472,309