Capital Stock - Additional Information (Detail) - USD ($)				9 Months Ended		17 Months Ended
	May 31, 2017	Mar. 30, 2017	May 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Jan. 31, 2017
Class Of Stock [Line Items]
Preference shares, shares authorized				20,000,000		20,000,000	20,000,000
Preference shares, par value				$ 0.00045		$ 0.00045	$ 0.00045
Preference shares, shares issued				0		0	0
Preference shares, shares outstanding				0		0	0
Ordinary shares, shares authorized				200,000,000		200,000,000	200,000,000
Stock repurchase program, period	12 months
Stock repurchase program, commencing date	Jul. 01, 2017
Stock repurchased during period, shares				1,028,048		1,433,137
Stock repurchased during period, cash				$ 51,505,000	$ 20,183,000	$ 71,700,000
Amount available under stock repurchase program				$ 35,000,000		$ 35,000,000
2012 Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance		1,501,606
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		417,112
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%
Stock Repurchase Program $75.0 Million Authorization [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorization date			May 31, 2016
Stock repurchase program, expiration date			Jun. 30, 2017
Stock Repurchase Program $75.0 Million Authorization [Member] | Maximum [Member]
Class Of Stock [Line Items]
Amount authorized under stock repurchase program			$ 75,000,000
Stock Repurchase Program $50.0 Million Authorization [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorization date	May 31, 2017
Stock repurchase program, expiration date	Jun. 30, 2018
Stock Repurchase Program $50.0 Million Authorization [Member] | Maximum [Member]
Class Of Stock [Line Items]
Amount authorized under stock repurchase program	$ 50,000,000