Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Income Statement [Abstract]
Revenue	$ 93,200	$ 65,689	$ 248,406	$ 153,578
Cost of revenue	31,938	24,130	86,378	55,887
Gross profit	61,262	41,559	162,028	97,691
Operating expenses:
Research and development	22,062	15,584	59,485	41,995
Selling, general and administrative	8,873	7,324	26,970	20,954
Total operating expenses	30,935	22,908	86,455	62,949
Income from operations	30,327	18,651	75,573	34,742
Other income	169	40	323	128
Income before income taxes	30,496	18,691	75,896	34,870
Provision for income taxes	1,035	364	4,484	1,973
Net income	$ 29,461	$ 18,327	$ 71,412	$ 32,897
Net income per share attributable to ordinary shareholders:
Basic	$ 0.93	$ 0.61	$ 2.27	$ 1.12
Diluted	$ 0.87	$ 0.57	$ 2.12	$ 1.03
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	31,815,588	30,006,896	31,476,668	29,467,178
Diluted	33,899,202	32,382,526	33,758,541	32,014,373