Investments - Summary of Investment Portfolio (Detail)	Mar. 31, 2020 USD ($) year Investment	Dec. 31, 2019 USD ($)
Investment Holdings [Line Items]
Number of debt investments on non accrual status \| Investment	0
Cost	$ 155,774,339	$ 133,274,339
Fair Value	$ 163,301,338	$ 144,195,000
Fair Value Percentage of Investment Portfolio	100.00%	100.00%
Fair Value Percentage of Net Assets	83.90%	82.70%
Total Senior Secured Notes
Investment Holdings [Line Items]
WeightedAverageYearsToMaturity \| year	4.1
Cost	$ 53,642,454	$ 48,167,603
Fair Value	$ 53,642,454	$ 48,167,603
Fair Value Percentage of Investment Portfolio	32.80%	33.40%
Fair Value Percentage of Net Assets	27.60%	27.60%
Senior secured debt - first lien
Investment Holdings [Line Items]
Cost	$ 17,700,000	$ 17,700,000
Fair Value	$ 17,700,000	$ 17,700,000
Fair Value Percentage of Investment Portfolio	10.80%	12.30%
Fair Value Percentage of Net Assets	9.10%	10.10%
Senior secured debt - second lien
Investment Holdings [Line Items]
Cost	$ 35,942,454	$ 30,467,603
Fair Value	$ 35,942,454	$ 30,467,603
Fair Value Percentage of Investment Portfolio	22.00%	21.10%
Fair Value Percentage of Net Assets	18.50%	17.50%
Equity
Investment Holdings [Line Items]
Cost	$ 102,131,885	$ 85,106,736
Fair Value	$ 109,658,884	$ 96,027,397
Fair Value Percentage of Investment Portfolio	67.20%	66.60%
Fair Value Percentage of Net Assets	56.30%	55.10%
Lawn Doctor, Inc.
Investment Holdings [Line Items]
Equity Method Investment, Ownership Percentage	62.00%
Polyform Products, Co.
Investment Holdings [Line Items]
Equity Method Investment, Ownership Percentage	87.00%
Roundtables [Member]
Investment Holdings [Line Items]
Equity Method Investment, Ownership Percentage	81.00%

Fair value percentage of investment portfolio.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Cost of the investment.

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Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Percent of net assets at close of period. For schedules of investments that are categorized, each category has a percent of net assets for the aggregated value of the Investments in the category.

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