Condensed Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013	Jul. 31, 2012
Income Statement [Abstract]
Revenue	$ 37,710	$ 27,958	$ 71,651	$ 53,879
Cost of revenue	14,419	8,626	26,667	16,142
Gross profit	23,291	19,332	44,984	37,737
Operating expenses:
Research and development	10,974	9,356	22,291	20,829
Selling, general and administrative	5,385	4,184	10,542	8,209
Total operating expenses	16,359	13,540	32,833	29,038
Income from operations	6,932	5,792	12,151	8,699
Other income (loss), net	(11)	4	(16)	2
Income before income taxes	6,921	5,796	12,135	8,701
Provision for income taxes	667	570	1,140	873
Net income	$ 6,254	$ 5,226	$ 10,995	$ 7,828
Net income per share attributable to ordinary shareholders:
Basic	$ 0.23	$ 0.20	$ 0.40	$ 0.28
Diluted	$ 0.21	$ 0.19	$ 0.37	$ 0.26
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	27,409,343	7,604,443	27,232,142	7,557,345
Diluted	29,848,676	9,114,927	29,456,374	9,068,762