Capital Stock - Additional Information (Detail) - USD ($)			6 Months Ended
	May 31, 2016	Feb. 01, 2016	Jul. 31, 2016	Jul. 31, 2015	Jan. 31, 2016
Class Of Stock [Line Items]
Preference shares, shares authorized			20,000,000		20,000,000
Preference shares, par value			$ 0.00045		$ 0.00045
Preference shares, shares issued			0		0
Preference shares, shares outstanding			0		0
Ordinary shares, shares authorized			200,000,000		200,000,000
Stock repurchase program, period	6 months
Stock repurchased during period, shares			405,089
Stock repurchased during period, cash			$ 20,183,000	$ 0
Maximum [Member]
Class Of Stock [Line Items]
Amount authorized under stock repurchase program	$ 75,000,000
2012 Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance		1,455,001
2012 Equity Incentive Plan [Member] | Scenario, plan automatically increased by the lessor of [Member]
Class Of Stock [Line Items]
Annual increase in ordinary shares for available for future issuance		3,500,000
Annual shares increase for future issuance by percentage under 2012 equity incentive plan		4.50%
Amended and Restated 2012 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance		404,166
Amended and Restated 2012 Employee Stock Purchase Plan [Member] | Scenario, plan automatically increased by the lessor of [Member]
Class Of Stock [Line Items]
Annual increase in ordinary shares for available for future issuance		1,500,000
Annual shares increase for future issuance by percentage under 2012 employee stock purchase plan		1.25%