Related-Party Transactions - Details of Amounts Due to Related Parties on Our Accompanying Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Related Party Transactions [Abstract]
Base management fee	$ 2,141	$ 1,836
Incentive fee	1,589	1,793
Other, net	80	95
Total due to Adviser	3,810	3,724
Administration fee	536	411
Cumulative accrued but unpaid portions of prior Administration Fees	0	89
Total due to Administrator	536	500
Total due to Gladstone Securities	24	0
Total due to related parties	$ 4,370	$ 4,224