Stock Based Compensation - Stock Option Award Activity - Additional Information (Detail) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Share-based compensation arrangement by share-based payment award, options, exercises in period, intrinsic value | $ 2,864,845 | $ 984,144 | $ 92,728 |
| Options granted | 0 | 0 | 0 |
| Employee Stock Option [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Employee service share-based compensation, nonvested awards, compensation not yet recognized, stock options | $ 0 | ||
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- Definition Unrecognized cost of unvested options awarded to employees as compensation. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Gross number of share options (or share units) granted during the period. No definition available.
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- Details
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