Financial Highlights - Schedule of Financial Highlights (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Per Share Data:
Par Amount	$ 21.12	$ 19.88	$ 19.50	$ 19.43	$ 20.10
Net investment income after tax	1.93	1.67	1.80	1.83	1.65
Net realized and unrealized gains (losses) on investments, asset acquisition and forward contracts, net of taxes	(1.43)	1.27	0.18	(0.14)	(0.89)
Net increase (decrease) in net assets resulting from operations	0.50	2.94	1.98	1.69	0.76
Effect of equity issuances, net of share repurchases and rounding		0.01	0.04	0.03	0.06
Distributions declared from net investment income	(1.79)	(1.69)	(1.64)	(1.64)	(1.47)
Offering Costs		(0.02)		(0.01)	(0.02)
Total increase (decrease) in net assets	(1.29)	1.24	0.38	0.07	(0.67)
Par Amount	$ 19.83	$ 21.12	$ 19.88	$ 19.50	$ 19.43
Shares outstanding, end of period	30,887,360	30,887,360	20,862,314	13,358,289	8,597,116
Market value, end of period	$ 12.78	$ 17.60	$ 14.57
Weighted average shares outstanding (basic):	30,887,360	28,477,771	27,681,757	17,344,640	10,719,485
Weighted average shares outstanding (diluted):	30,887,360	28,477,771	27,681,757	17,344,640	10,719,485
Total return based on market value	(18.45%)	32.46%	1.47%
Total return based on net asset value	2.37%	14.74%	10.36%	8.81%	4.06%
Ratio/Supplemental Data:
Net assets, end of period	$ 612,541	$ 652,285	$ 560,000	$ 406,917	$ 259,579
Ratio of total net expenses to average net assets	8.96%	7.81%	5.34%	6.54%	7.33%
Ratio of net expenses (without incentive fees and interest and other debt expenses) to average net assets	3.26%	3.02%	2.24%	2.50%	3.06%
Ratio of net investment income before taxes to average net assets	9.41%	8.40%	10.10%	9.61%	8.48%
Ratio of interest and credit facility expenses to average net assets	5.01%	3.33%	3.10%	4.03%	4.01%
Ratio of net incentive fees to average net assets	0.68%	1.46%			0.26%
Portfolio turnover	21.52%	41.64%	28.01%	23.97%	27.89%
Asset coverage ratio	192.00%	201.00%	217.00%	225.00%	209.00%