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
	Apr. 30, 2013	Apr. 30, 2012
Numerator:
Net income	$ 4,741	$ 2,602
Less: amount allocable to preference shareholders		(2,028)
Less: amount allocable to unvested early exercised options	(9)	(8)
Net income allocable to ordinary shareholders - basic	4,732	566
Undistributed earnings reallocated to ordinary shareholders	1	68
Net income allocable to ordinary shareholders - diluted	$ 4,733	$ 634
Denominator:
Weighted-average ordinary shares outstanding	27,103,129	7,622,621
Less: weighted-average unvested early exercised options subject to repurchase	(46,197)	(103,261)
Weighted-average ordinary shares - basic	27,056,932	7,519,360
Effect of potentially dilutive securities:
Employee stock options	1,688,768	1,512,350
Restricted stock units	141,647
Employee stock purchase plan	170,817
Warrants to purchase ordinary shares	7,898
Weighted-average ordinary shares - diluted	29,066,062	9,031,710
Net income per ordinary share:
Basic	$ 0.17	$ 0.08
Diluted	$ 0.16	$ 0.07