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Equity Incentive Plan - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended |
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Jun. 03, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Tax effect for stock-based compensation benefit (expense) for option and restricted stock units exercised | $ 11 | $ (49) | $ 177 |
Employee Stock Options And Restricted Stock Units [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Tax effect for stock-based compensation benefit (expense) for option and restricted stock units exercised | $ 2,188 | $ 3,446 | $ 2,211 |
2005 Equity Incentive Plan | Restricted Stock Units |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Conversion ratio of restricted stock unit to ordinary shares | one-for-one |  |  |
2015 Equity Incentive Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Ordinary shares authorized |  |  |  | 20,000,000
The 2005 Plan and The 2015 Plan | Restricted Stock Units |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Total unrecognized compensation cost related to non-vested share-based compensation | $ 3,116 |  |  |

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