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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
Operating Loss Carryforwards [Line Items] |  |  |
Federal corporate tax rate | 21.00% | 35.00% | 35.00%
Deferred tax liability related to foreign earnings | $ 0 |  |
Excess tax shortfall (benefit) from exercise of share-based awards | $ (2,000,000) | $ 900,000 | $ 1,100,000
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 | $ 600,000 |  |
Net operating losses carryforwards, expiration year | 2023 |  |

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