Portfolio Company Investments - Schedule of Consolidated Schedule of Investments in and Advances to Affiliates (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Control Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments	$ 14,576	$ 5,226
Fair Value, beginning balance	2,151	28,253
Gross Additions	20,174	41,485
Gross Reductions	(22,325)	(67,587)
Fair Value, ending balance		2,151
Net Realized Gain (Losses)	(158)	20,521
Net Change in Unrealized Appreciation (Depreciation)	(13,233)	34
Interest Income		3,735
Payment-in-kind Interest Income		2,117
Dividend Income		568
Fee Income		1,872
Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments	34,602	29,307
Fair Value, beginning balance	137,284	81,394
Gross Additions	70,477	72,005
Gross Reductions	(106,171)	(16,115)
Fair Value, ending balance	101,590	137,284
Net Realized Gain (Losses)	39,833	94
Net Change in Unrealized Appreciation (Depreciation)	(35,979)	32,207
Interest Income	3,464	2,695
Payment-in-kind Interest Income	30	368
Dividend Income	725	1,172
Fee Income	457	385
EBL, LLC (EbLens) \| Control Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments	9,350
Gross Additions	19,628
Gross Reductions	(19,628)
Net Change in Unrealized Appreciation (Depreciation)	(11,083)
Hilco Plastics Holdings, LLC (dba Hilco Technologies) \| Control Investments
Investments in and Advances to Affiliates [Line Items]
Gross Additions	353	1,577
Gross Reductions	(353)	(1,577)
Net Realized Gain (Losses)	(352)	(881)
Interest Income		308
Dividend Income		568
Mesa Line Services, LLC \| Control Investments
Investments in and Advances to Affiliates [Line Items]
Fair Value, beginning balance	2,151
Gross Additions	193	32,708
Gross Reductions	(2,344)	(30,557)
Fair Value, ending balance		2,151
Net Realized Gain (Losses)	194	20,445
Net Change in Unrealized Appreciation (Depreciation)	(2,150)	2,150
Interest Income		951
Payment-in-kind Interest Income		903
Fee Income		1,472
US GreenFiber, LLC \| Control Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments	5,226	5,226
Fair Value, beginning balance		20,862
Gross Additions		5,214
Gross Reductions		(26,076)
Net Change in Unrealized Appreciation (Depreciation)		(3,144)
Interest Income		2,386
Payment-in-kind Interest Income		1,214
Applegate Greenfiber Intermediate Inc. (fka US GreenFiber, LLC) \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments	9,602	9,602
Fair Value, beginning balance	22,405
Gross Additions	13,566	22,405
Gross Reductions	(12,803)
Fair Value, ending balance	23,168	22,405
Net Change in Unrealized Appreciation (Depreciation)	763
Interest Income	973
FAR Research Inc. \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Fair Value, beginning balance	28	28
Gross Reductions	(28)
Fair Value, ending balance		28
Net Change in Unrealized Appreciation (Depreciation)	(28)
Fiber Materials, Inc. \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Fair Value, beginning balance		41
Gross Additions		94
Gross Reductions		(135)
Net Realized Gain (Losses)		94
Net Change in Unrealized Appreciation (Depreciation)		(42)
Medsurant Holdings, LLC \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Fair Value, beginning balance	3,662	10,960
Gross Additions		733
Gross Reductions	(1,122)	(8,031)
Fair Value, ending balance	2,540	3,662
Net Change in Unrealized Appreciation (Depreciation)	(1,122)	687
Interest Income		331
Fee Income		91
Mirage Trailers LLC \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments		6,705
Fair Value, beginning balance	10,675	6,494
Gross Additions	355	4,225
Gross Reductions	(11,030)	(44)
Fair Value, ending balance		10,675
Net Realized Gain (Losses)	324
Net Change in Unrealized Appreciation (Depreciation)	(1,694)	3,871
Interest Income	248	761
Payment-in-kind Interest Income	29	338
Dividend Income		110
Fee Income	132
Pfanstiehl, Inc \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments	10,000
Fair Value, beginning balance	57,639	33,505
Gross Additions	34,335	24,134
Gross Reductions	(39,982)
Fair Value, ending balance	51,992	57,639
Net Realized Gain (Losses)	24,330
Net Change in Unrealized Appreciation (Depreciation)	(15,432)	24,135
Interest Income	421
Dividend Income		1,062
Fee Income	150
Pinnergy, Ltd. \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Fair Value, beginning balance	21,178	20,589
Gross Additions	15,300	589
Gross Reductions	(36,478)
Fair Value, ending balance		21,178
Net Realized Gain (Losses)	15,300
Net Change in Unrealized Appreciation (Depreciation)	(18,177)	589
Dividend Income	656
Spectra A&D Acquisition, Inc. (fka FDS Avionics Corp.) \| Control Investments
Investments in and Advances to Affiliates [Line Items]
Fair Value, beginning balance		7,391
Gross Additions		1,986
Gross Reductions		(9,377)
Net Realized Gain (Losses)		957
Net Change in Unrealized Appreciation (Depreciation)		1,028
Interest Income		90
Fee Income		400
Spectra A&D Acquisition, Inc. (fka FDS Avionics Corp.) \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Principal Amount - Debt Investments	15,000	13,000
Fair Value, beginning balance	18,359
Gross Additions	5,487	18,452
Gross Reductions	(4,728)	(93)
Fair Value, ending balance	19,118	18,359
Net Realized Gain (Losses)	(121)
Net Change in Unrealized Appreciation (Depreciation)	(1,723)	1,626
Interest Income	1,822	1,142
Fee Income	175	294
Steward Holding LLC (dba Steward Advanced Materials) \| Affiliate Investments
Investments in and Advances to Affiliates [Line Items]
Fair Value, beginning balance	3,338	9,777
Gross Additions	1,434	1,373
Gross Reductions		(7,812)
Fair Value, ending balance	4,772	3,338
Net Change in Unrealized Appreciation (Depreciation)	1,434	1,341
Interest Income		461
Payment-in-kind Interest Income	1	$ 30
Dividend Income	$ 69

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Value of the investment at close of period. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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