Capital Stock - Additional Information (Detail) - USD ($)				3 Months Ended	47 Months Ended
	Mar. 16, 2020	Feb. 01, 2020	Jun. 30, 2016	Apr. 30, 2020	Apr. 30, 2020	Jan. 31, 2020
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 repurchased, shares	25,719				4,011,595
Stock repurchased during period, cash	$ 1,000,000.0			$ 1,000,000	$ 175,800,000
Stock repurchase program, inception period			2016-06
Amount authorized under stock repurchase program				275,000,000.0	275,000,000.0
Amount available under stock repurchase program				$ 49,000,000.0	$ 49,000,000.0
2012 Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Additional ordinary shares reserved for issuance		1,521,252
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		422,570
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%