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Share-Based Compensation -Schedule of Nonvested Restricted Stock Units Activity (Parenthetical) (Detail) | 9 Months Ended
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Sep. 30, 2020 shares
Schedule Of Nonvested Restricted Stock Units Activity [Line Items] |
Share based compensation by share based payment arrangement additional number of shares authorized for grant | 91,051
Special Award [Member] | 2018 Plan [Member] |
Schedule Of Nonvested Restricted Stock Units Activity [Line Items] |
Share based compensation by share based payment arrangement additional number of shares authorized for grant | 1,446,875

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