Alcentra Acquisition - Additional Information (Details) $ / shares in Units, $ in Thousands				12 Months Ended	18 Months Ended
		Jan. 31, 2020 USD ($) $ / shares shares	Aug. 12, 2019 $ / shares	Dec. 31, 2020 USD ($)	Jul. 31, 2021	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 $ / shares shares
Business Acquisition [Line Items]
Common stock, par value | $ / shares						$ 0.001	$ 0.001
Common stock, outstanding | shares						30,887,360	30,887,360
Realized loss on asset acquisition	[1]			$ (3,825)
Alcentra Acquisition
Business Acquisition [Line Items]
Business acquisition date			Aug. 12, 2019
Business Acquisition Completion Date		Jan. 31, 2020
Cash consideration per share | $ / shares		$ 1.50
Dividend declared | $ / shares		$ 0.80
Stock consideration fixed exchange ratio		40.4100
Common stock, par value | $ / shares		$ 0.001
Common stock, outstanding | shares		12,875,566
Number of shares issued in merger | shares		5,203,016
Cash consideration per share | $ / shares			$ 1.68
Alcentra acquisition expenses		$ 7,250
Adviser transaction support fee		1,419
Realized loss on asset acquisition		(3,825)
Total cash and stock consideration		118,256
Alcentra Acquisition | Transaction Support Agreement
Business Acquisition [Line Items]
Management fee percentage			1.50%
Management fee reduced percentage			1.25%
Incentive fee percentage			6.00%
Increased incentive fee percentage			7.00%
Waived portion of management fees percentage					0.75%
Alcentra acquisition expenses		$ 1,419

[1] After the close of business on January 31, 2020, in connection with the Alcentra Acquisition (as defined in Note 1 and further discussed in Note 14), the Company acquired net assets of $114,431 which included $195,682 of investments, $3,409 cash and cash equivalents and $1,398 of other assets, net of $86,058 of assumed liabilities, for the total cash and stock consideration of $118,256, inclusive of $7,250 of asset acquisition costs.