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Stock Based Compensation - Employee Stock Purchase Plan - Additional Information (Detail) - Employee Stock Purchase Plan [Member] - USD ($) | 3 Months Ended | 6 Months Ended
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Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value |  |  | $ 0.57 | $ 2.43
Percentage of proportionate value of call option of stock |  |  | 85.00% |
Percentage of proportionate value of put option of stock |  |  | 15.00% |
Allocated share-based compensation expense | $ 41,308 | $ 122,749 | $ 84,135 | $ 210,574

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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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