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Income Taxes - Additional Information (Detail) - USD ($) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Operating Loss Carryforwards [Line Items] |  |  |  |
Federal corporate tax rate |  | 35.00% | 35.00% | 35.00%
Net tax benefit recognized due to re-measurement of deferred tax liabilities |  | $ 102,800,000 |  |
Provisional income tax expense related to deemed repatriation of foreign earnings |  | 300,000 |  |
Deferred tax liability related to foreign earnings |  | $ 0 |  |
Term of finalizing provision |  | 1 year |  |
Excess tax shortfall (benefit) from exercise of share-based awards |  | $ (900,000) | $ 1,100,000 | $ 300,000
Likelihood percentage of being realized upon ultimate settlement with the relevant tax authority |  | 50.00% |  |
Unrecognized tax benefits |  | $ 0 | 0 |
Changes in unrecognized benefits |  | 0 | $ 0 | $ 0
Foreign [Member] |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |
Net operating losses carryforwards |  | $ 400,000 |  |
Net operating losses carryforwards, expiration year |  | 2023 |  |
Scenario Forecast [Member] |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |
Federal corporate tax rate | 21.00% |  |  |

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