Capital Stock - Additional Information (Detail) - USD ($)
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3 Months Ended |
35 Months Ended |
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Feb. 01, 2019 |
Jun. 04, 2018 |
Apr. 30, 2019 |
Apr. 30, 2018 |
Apr. 30, 2019 |
Jan. 31, 2019 |
| Class Of Stock [Line Items] |
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| Preference shares, shares authorized |
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20,000,000
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20,000,000
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20,000,000
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| Preference shares, par value |
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$ 0.00045
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$ 0.00045
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$ 0.00045
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| Preference shares, shares issued |
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0
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0
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0
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| Preference shares, shares outstanding |
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0
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0
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0
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| Ordinary shares, shares authorized |
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200,000,000
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200,000,000
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200,000,000
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| Stock repurchased during period, shares |
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0
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3,985,876
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| Stock repurchased during period, cash |
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$ 0
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$ 20,624,000
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$ 174,800,000
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| 2012 Equity Incentive Plan [Member] |
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| Class Of Stock [Line Items] |
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| Additional ordinary shares reserved for issuance |
1,453,659
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| 2012 Equity Incentive Plan [Member] | Scenario, plan automatically increased by the lessor of [Member] |
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| Class Of Stock [Line Items] |
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| Annual increase in ordinary shares for available for future issuance |
3,500,000
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| Annual shares increase for future issuance by percentage under 2012 equity incentive plan |
4.50%
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| Amended and Restated 2012 Employee Stock Purchase Plan [Member] |
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| Class Of Stock [Line Items] |
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| Additional ordinary shares reserved for issuance |
403,794
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| Amended and Restated 2012 Employee Stock Purchase Plan [Member] | Scenario, plan automatically increased by the lessor of [Member] |
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| Class Of Stock [Line Items] |
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| Annual increase in ordinary shares for available for future issuance |
1,500,000
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| Annual shares increase for future issuance by percentage under 2012 employee stock purchase plan |
1.25%
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| Stock Repurchase Program $100.0 Million Authorization [Member] |
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| Class Of Stock [Line Items] |
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| Stock repurchase program, authorization date |
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Jun. 04, 2018
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| Stock repurchase program, period |
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12 months
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| Stock repurchase program, commencing date |
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Jun. 05, 2018
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| Stock Repurchase Program $100.0 Million Authorization [Member] | Maximum [Member] |
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| Class Of Stock [Line Items] |
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| Amount authorized under stock repurchase program |
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$ 100,000,000
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