Net Income Per Ordinary Share - Computation of Basic and Diluted Net Income Per Ordinary Share (Detail) (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
Numerator:
Net income	$ 6,254	$ 5,226	$ 10,995	$ 7,828
Less: amount allocable to preference shareholders		(3,689)		(5,719)
Less: amount allocable to unvested early exercised options	(8)	(15)	(17)	(26)
Net income allocable to ordinary shareholders - basic	6,246	1,522	10,978	2,083
Undistributed earnings reallocated to ordinary shareholders	1	179	1	248
Net income allocable to ordinary shareholders - diluted	$ 6,247	$ 1,701	$ 10,979	$ 2,331
Denominator:
Weighted-average ordinary shares outstanding	27,443,622	7,679,674	27,273,376	7,651,418
Less: weighted-average unvested early exercised options subject to repurchase	(34,279)	(75,231)	(41,234)	(94,073)
Weighted-average ordinary shares - basic	27,409,343	7,604,443	27,232,142	7,557,345
Effect of potentially dilutive securities:
Employee stock options	2,046,623	1,510,484	1,867,695	1,511,417
Restricted stock units	159,434		150,541
Employee stock purchase plan	231,278		201,048
Warrants to purchase ordinary shares	1,998		4,948
Weighted-average ordinary shares - diluted	29,848,676	9,114,927	29,456,374	9,068,762
Net income per ordinary share:
Basic	$ 0.23	$ 0.20	$ 0.40	$ 0.28
Diluted	$ 0.21	$ 0.19	$ 0.37	$ 0.26