Fair Value Measurements - Summary of Valuation of Investments by Fair Value Hierarchy Levels (Detail) - USD ($)		Jun. 30, 2020	Dec. 31, 2019
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		$ 330,593,500	$ 340,298,376
Senior Secured Term Loans [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value	[1]	99,415,415	83,353,208
Senior Secured Term Loan Participations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value	[1]	158,424,908	180,500,425
Senior Secured Trade Finance Participations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value	[1]	67,795,496	71,606,458
Other Investments [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		3,758,063
Equity Warrants [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		1,199,618	1,080,222
Short Term Investments [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value			3,758,063
Level 3 [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		330,593,500	340,298,376
Level 3 [Member] | Senior Secured Term Loans [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		99,415,415	83,353,208
Level 3 [Member] | Senior Secured Term Loan Participations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		158,424,908	180,500,425
Level 3 [Member] | Senior Secured Trade Finance Participations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		67,795,496	71,606,458
Level 3 [Member] | Other Investments [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value	[2]	3,758,063	3,758,063
Level 3 [Member] | Equity Warrants [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value		$ 1,199,618	1,080,222
Level 3 [Member] | Short Term Investments [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investments, fair value			$ 3,758,063

[1] Refer to Notes 2, 3 and 4 of the consolidated financial statements for additional information on the Company’s investments.

[2] Receivable from IIG TOF B.V. using additional discount rate of 20%.