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		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Numerator:
Net income	$ 9,126	$ 6,717	$ 20,121	$ 14,545
Less: amount allocable to preference shareholders		(3,456)		(9,517)
Less: amount allocable to unvested early exercised options	(8)	(18)	(27)	(53)
Net income allocable to ordinary shareholders - basic	9,118	3,243	20,094	4,975
Undistributed earnings reallocated to ordinary shareholders		155	2	432
Net income allocable to ordinary shareholders - diluted	$ 9,118	$ 3,398	$ 20,096	$ 5,407
Denominator:
Weighted-average ordinary shares outstanding	27,861,176	12,137,555	27,469,309	9,146,617
Less: weighted-average unvested early exercised options subject to repurchase	(25,090)	(68,736)	(37,008)	(96,753)
Weighted-average ordinary shares - basic	27,836,086	12,068,819	27,432,301	9,049,864
Effect of potentially dilutive securities:
Employee stock options	2,082,777	1,346,272	1,939,389	1,456,429
Restricted stock units	313,832		204,971
Employee stock purchase plan	122,535		174,877
Warrants to purchase ordinary shares			3,299
Weighted-average ordinary shares - diluted	30,355,230	13,415,091	29,754,837	10,506,293
Net income per ordinary share:
Basic	$ 0.33	$ 0.27	$ 0.73	$ 0.55
Diluted	$ 0.30	$ 0.25	$ 0.68	$ 0.51