FINANCIAL HIGHLIGHTS (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares
Per Share Data:(1)
Net asset value at beginning of period	$ 14.61	$ 14.03	$ 14.14	$ 14.09	$ 13.81	$ 13.69	$ 13.19	$ 13.94	$ 14.54	$ 14.45
Net investment income	1.46	1.01	1.13	1.23	1.42	1.21	1.39	1.33	1.34	1.33
Change in unrealized (depreciation) appreciation on investments	(0.90)	(0.36)	0.44	(0.85)	(0.11)		1.49	(0.74)	(0.53)	0.03
Net realized gain (loss)	0.19	1.22	(0.52)	1.07	0.35	0.31	(1.05)	0.03	0.04	0.09
Loss on debt extinguishment		(0.03)
Provision for taxes on realized gains		(0.15)			(0.02)
(Provision) benefit for taxes on net unrealized (appreciation) depreciation on investments	(0.01)	0.03	(0.01)				0.03	(0.01)	(0.02)
Total from operations	0.74	1.72	1.04	1.45	1.64	1.52	1.86	0.61	0.83	1.45
Sales load				(0.06)		(0.09)			(0.01)
Offering costs	(0.03)			(0.03)		(0.02)
Net investment income	(1.11)	(1.09)	(1.15)	(0.54)	(1.03)	(1.20)	(1.36)	(1.33)	(1.31)	(1.36)
Net realized capital gains	(0.19)	(0.05)		(0.82)	(0.33)	(0.16)		(0.03)	(0.12)
Other				0.05		0.07			0.01
Net asset value at end of period	14.02	14.61	14.03	14.14	14.09	13.81	13.69	13.19	13.94	14.54
Per share market value at end of period	$ 13.26	$ 13.02	$ 10.88	$ 14.23	$ 12.95	$ 13.14	$ 12.06	$ 9.64	$ 11.78	$ 14.95
Total return based on market value(2)	12.32%	30.78%	(13.73%)	21.97%	8.68%	20.29%	42.83%	(7.76%)	(13.09%)	0.42%
Weighted Average Shares of Common Stock Outstanding Basic | shares	19,552,931	19,489,750	19,471,500	18,275,696	15,953,571	14,870,981	12,479,959	12,479,961	12,281,178	12,059,293
Weighted Average Shares of Common Stock Outstanding Diluted | shares	19,552,931	19,489,750	19,471,500	18,275,696	15,953,571	14,870,981	12,479,959	12,479,961	12,281,178	12,059,293
Ratio/Supplemental Data:(1)
Net assets at end of period | $	$ 275,776,613	$ 285,111,233	$ 273,360,649	$ 270,571,173	$ 224,845,007	$ 220,247,242	$ 170,881,785	$ 164,651,104	$ 173,949,452	$ 175,891,514
Weighted average net assets | $	$ 281,745,332	$ 274,188,692	$ 253,034,571	$ 259,020,507	$ 223,750,302	$ 195,211,550	$ 165,189,142	$ 173,453,813	$ 176,458,141	$ 175,398,660
Annualized ratio of gross operating expenses to net assets(5)	16.59	16.90	13.75	14.11	13.72	11.10	13.20	11.16	9.92	8.65
Annualized ratio of net operating expenses to net assets(7)(8)						11.10	13.20	10.78	9.12	7.63
Annualized ratio of interest expense and other fees to net assets	8.68	6.83	6.29	5.78	5.51	4.02	4.84	3.56	3.01	1.78
Annualized ratio of net investment income before fee waiver to net assets(7)						9.21	10.71	9.11	8.40	8.11
Annualized ratio of net investment income to net assets(5)	10.15%	7.21%	8.58%	8.64%	10.09%	9.21%	10.71%	9.49%	9.19%	9.13%
Portfolio turnover(3)	15.26	39.00	21.00	23.00	32.00	48.00	16	29	19	41
Notes payable | $	$ 98,549,692	$ 98,102,973	$ 48,875,000	$ 48,875,000	$ 48,875,000	$ 48,875,000	$ 25,000,000	$ 25,000,000	$ 25,000,000	$ 110,000,000
Credit Facility payable | $	199,200,425	177,340,000	174,000,000	161,550,000	99,550,000
SBA-guaranteed debentures | $	$ 313,600,000	$ 250,000,000	$ 176,500,000	$ 161,000,000	$ 150,000,000	$ 90,000,000	$ 65,000,000	$ 65,000,000	$ 16,250,000
Asset coverage ratio(4)	1.92	2.03	2.23	2.29	2.51	3.46	2.21	2.22	2.32	2.48
Debt extinguishment costs | $		$ (539,250)				$ (416,725)
Debt extinguishment cost ratio		7.02%				4.24%
(Provision) benefit for taxes on net unrealized (appreciation) depreciation on investments | $	$ (213,214)	$ 510,868	$ (224,877)	$ (66,760)			$ 373,131	$ (93,601)	$ (288,122)
Provision for taxes on realized gain on investments | $		$ (2,957,220)
Impact of tax provision benefit on net realized gain (loss) or unrealized (appreciation) depreciation to net assets	(0.08%)	(0.89%)	(0.09%)	(0.03%)			(0.16%)	0.05%	0.17%
Deferred offering costs | $	$ 1,100	$ 14,888					$ 261,761