Investments - Schedule of Investment by Geographical Classification (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Fair Value	$ 330,593,500	$ 340,298,376
Percentage of Total Investments	100.00%	100.00%
Argentina [Member]
Schedule of Investments [Line Items]
Fair Value	$ 24,159,256	$ 24,198,860
Percentage of Total Investments	7.30%	7.10%
Botswana [Member]
Schedule of Investments [Line Items]
Fair Value	$ 4,740,000	$ 4,740,000
Percentage of Total Investments	1.40%	1.40%
Brazil [Member]
Schedule of Investments [Line Items]
Fair Value	$ 26,393,798	$ 26,012,563
Percentage of Total Investments	8.00%	7.60%
Cabo Verde [Member]
Schedule of Investments [Line Items]
Fair Value	$ 11,359,874	$ 12,846,584
Percentage of Total Investments	3.40%	3.80%
Cameroon [Member]
Schedule of Investments [Line Items]
Fair Value	$ 9,192,637	$ 9,687,887
Percentage of Total Investments	2.80%	2.90%
Chile [Member]
Schedule of Investments [Line Items]
Fair Value	$ 2,678,224	$ 2,652,855
Percentage of Total Investments	0.80%	0.80%
Colombia [Member]
Schedule of Investments [Line Items]
Fair Value	$ 23,456,424	$ 23,479,065
Percentage of Total Investments	7.10%	6.90%
Croatia [Member]
Schedule of Investments [Line Items]
Fair Value	$ 8,786,977	$ 8,638,109
Percentage of Total Investments	2.70%	2.50%
Ecuador [Member]
Schedule of Investments [Line Items]
Fair Value	$ 13,387,573	$ 35,838
Percentage of Total Investments	4.10%	0.00%
Ghana [Member]
Schedule of Investments [Line Items]
Fair Value	$ 14,592,683	$ 30,500,000
Percentage of Total Investments	4.40%	9.00%
Guatemala [Member]
Schedule of Investments [Line Items]
Fair Value	$ 10,504	$ 10,504
Percentage of Total Investments	0.00%	0.00%
Hong Kong [Member]
Schedule of Investments [Line Items]
Fair Value	$ 49,646,085	$ 51,188,138
Percentage of Total Investments	15.00%	15.00%
Jersey [Member]
Schedule of Investments [Line Items]
Fair Value	$ 15,266,500	$ 16,919,500
Percentage of Total Investments	4.60%	5.00%
Kenya [Member]
Schedule of Investments [Line Items]
Fair Value	$ 13,779,518	$ 13,505,035
Percentage of Total Investments	4.20%	4.00%
Malaysia [Member]
Schedule of Investments [Line Items]
Fair Value	$ 15,000,000	$ 15,000,000
Percentage of Total Investments	4.50%	4.40%
Mauritius [Member]
Schedule of Investments [Line Items]
Fair Value	$ 457,418	$ 468,756
Percentage of Total Investments	0.10%	0.10%
Mexico [Member]
Schedule of Investments [Line Items]
Fair Value	$ 27,738,539	$ 25,766,063
Percentage of Total Investments	8.40%	7.60%
Morocco [Member]
Schedule of Investments [Line Items]
Fair Value	$ 7,530,616	$ 7,530,616
Percentage of Total Investments	2.30%	2.20%
Namibia [Member]
Schedule of Investments [Line Items]
Fair Value	$ 14,873,425	$ 16,781,000
Percentage of Total Investments	4.50%	4.90%
Netherlands [Member]
Schedule of Investments [Line Items]
Fair Value	$ 8,974,373	$ 8,731,936
Percentage of Total Investments	2.70%	2.60%
New Zealand [Member]
Schedule of Investments [Line Items]
Fair Value	$ 5,797,622	$ 5,612,436
Percentage of Total Investments	1.80%	1.70%
Nigeria [Member]
Schedule of Investments [Line Items]
Fair Value	$ 12,030,084	$ 14,262,726
Percentage of Total Investments	3.60%	4.20%
Peru [Member]
Schedule of Investments [Line Items]
Fair Value	$ 4,599,086	$ 4,599,086
Percentage of Total Investments	1.40%	1.40%
Romania [Member]
Schedule of Investments [Line Items]
Fair Value	$ 1,744,775	$ 2,034,188
Percentage of Total Investments	0.50%	0.60%
South Africa [Member]
Schedule of Investments [Line Items]
Fair Value	$ 497,462	$ 790,616
Percentage of Total Investments	0.20%	0.20%
United Arab Emirates [Member]
Schedule of Investments [Line Items]
Fair Value	$ 648,430	$ 803,254
Percentage of Total Investments	0.20%	0.20%
Uganda [Member]
Schedule of Investments [Line Items]
Fair Value	$ 6,873,472	$ 6,850,000
Percentage of Total Investments	2.10%	2.00%
Zambia [Member]
Schedule of Investments [Line Items]
Fair Value	$ 2,620,083	$ 2,894,698
Percentage of Total Investments	0.80%	0.90%
Other [Member]
Schedule of Investments [Line Items]
Fair Value	$ 3,758,062	$ 3,758,063
Percentage of Total Investments	1.10%	1.10%