Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	6 Months Ended
Jun. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Restricted cash	$ 6,776,588	$ 8,683,095
Cash denominated in foreign currencies	(641,657)	977,236
Cash denominated in foreign currencies, proceeds	649,859
Cash denominated in foreign currencies, cost		$ 984,412
Provision for income tax	0
Uncertain tax position	$ 0
Open tax year	2014 2015 2016 2017

Cash held in fund denominated in foreign currency.

No definition available.

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- Definition

Cash held in fund denominated in foreign currency at cost.

+ References

No definition available.

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- Definition

Cash held in fund denominated in foreign currency proceeds.

+ References

No definition available.

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- References

No definition available.

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- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount recognized for uncertainty in income taxes classified as current.

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- Definition

Tax year that remains open to examination under enacted tax laws, in CCYY format.

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- Definition

Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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