| Significant Accounting Policies - Additional Information (Detail) - USD ($) | Mar. 31, 2018 | Dec. 31, 2017 | 
|---|---|---|
| Accounting Policies [Abstract] | ||
| Uninsured portion of cash balance | $ 4,507,863 | $ 5,916,143 | 
| X | ||||||||||
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- References No definition available. 
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| X | ||||||||||
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- Definition The amount of cash as of the balance sheet date that is not insured by the Federal Deposit Insurance Corporation. No definition available. 
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