Fair Value of Financial Instruments - Reconciliations of Investments of Level 3 Inputs (Detail) - Level 3	12 Months Ended
	Dec. 31, 2019 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements)	$ 56,500,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value balance, beginning	82,500,000
Net change in unrealized appreciation	5,195,000
Fair value balance, ending	144,195,000
Total Senior Secured Notes
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements)	17,467,603
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value balance, beginning	30,700,000
Net change in unrealized appreciation	0
Fair value balance, ending	48,167,603
Equity
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements)	39,032,397
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value balance, beginning	51,800,000
Net change in unrealized appreciation	5,195,000
Fair value balance, ending	$ 96,027,397