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Summary of Significant Accounting Policies - Summary of Distributions Per Share and in Total (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Accounting Policies [Abstract]        
Distributions per Share $ 0.15 $ 0.10 $ 0.43 $ 0.18
Distributions paid $ 250,082 $ 206,624 $ 753,725 $ 381,372