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Retirement Plan - Additional Information (Detail) - USD ($) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Compensation And Retirement Disclosure [Abstract] |  |  |
Retirement plan, employees maximum pre-tax contributions percentage | 60.00% |  |
Contributions to 401(k) plan | $ 0 | $ 0 | $ 0

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- References No definition available. + Details
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- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
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- Definition Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan. + References No definition available. + Details
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