Condensed Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Income Statement [Abstract]
Revenue	$ 45,990	$ 35,669	$ 117,641	$ 89,548
Cost of revenue	16,689	12,679	43,356	28,821
Gross profit	29,301	22,990	74,285	60,727
Operating expenses
Research and development	13,476	10,802	35,767	31,631
Selling, general and administrative	5,761	4,603	16,303	12,812
Total operating expenses	19,237	15,405	52,070	44,443
Income from operations	10,064	7,585	22,215	16,284
Other income (loss), net	(12)	137	(28)	139
Income before income taxes	10,052	7,722	22,187	16,423
Provision for income taxes	926	1,005	2,066	1,878
Net income	$ 9,126	$ 6,717	$ 20,121	$ 14,545
Net income per share attributable to ordinary shareholders:
Basic	$ 0.33	$ 0.27	$ 0.73	$ 0.55
Diluted	$ 0.30	$ 0.25	$ 0.68	$ 0.51
Weighted-average shares used to compute net income per share attributable to ordinary shareholders:
Basic	27,836,086	12,068,819	27,432,301	9,049,864
Diluted	30,355,230	13,415,091	29,754,837	10,506,293