Transactions with Affiliated Companies - Fair Value Roll Forward (Details) - USD ($) $ in Thousands		6 Months Ended		12 Months Ended
	Dec. 29, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 541,040
Fair value at the ending		$ 515,407		$ 541,040
Stock issued (in shares)	4,940
Percentage of preferred units obtained	22.30%
Investment, Identifier [Axis]: 360 Holdco, Inc. ( Delayed Draw), Senior Secured Loans, due 8/2/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, Two, due 8/1/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ThreeSixty360HoldcoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 825
Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, due 8/1/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ThreeSixty360HoldcoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,135
Investment, Identifier [Axis]: 360 Holdco, Inc., Senior Secured Loans, due 8/2/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: A P C O Worldwide, Inc, Equity Securities, Class A voting common stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:APCOWorldwideIncMember		mrcc:APCOWorldwideIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 921
Fair value at the ending		$ 1,149		$ 921
Number of shares held		100
Number of units held				100
Investment, Identifier [Axis]: A Q Carver Buyer, Inc., Senior Secured Loans, due 9/23/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AQCarverBuyerIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,825
Investment, Identifier [Axis]: A S G I I, L L C ( Delayed Draw), Unitranche Secured Loans, 5/25/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ASGIILLCMember		mrcc:ASGIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 51
Fair value at the ending		$ 111		$ 51
Investment, Identifier [Axis]: A S G I I, L L C, Unitranche Secured Loans, due 5/25/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ASGIILLCMember		mrcc:ASGIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,900
Fair value at the ending		$ 1,900		$ 1,900
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Delayed Draw), Senior Secured Loans, due 12/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C ( Revolver), Senior Secured Loans, due 12/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Accelerate Auto Works Intermediate, L L C, Senior Secured Loans, due 12/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Ad Theorent Holding Company, Inc. Equity Securities, common stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AdTheorentHoldingCompanyIncMember		mrcc:AdTheorentHoldingCompanyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 294
Fair value at the ending		$ 248		$ 294
Number of shares held		177,362		177,362
Investment, Identifier [Axis]: Amelia Holding II, LLC (Delayed Draw), Due 12/21/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AmeliaHoldingIiLlcDelayedDrawMember		mrcc:AmeliaHoldingIiLlcMember
Investment, Identifier [Axis]: Amelia Holding II, LLC (Revolver), Due 12/21/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AmeliaHoldingIiLlcRevolverMember		mrcc:AmeliaHoldingIiLlcMember
Investment, Identifier [Axis]: Amelia Holding II, LLC, Due 12/21/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AmeliaHoldingIiLlcMember		mrcc:AmeliaHoldingIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,940
Fair value at the ending		$ 2,003		$ 1,940
Investment, Identifier [Axis]: Amelia Holding II, LLC, Equity Securities
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AmeliaHoldingIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 27
Number of units held		0.1
Investment, Identifier [Axis]: Amelia Holding II, LLC, Equity Securities, Warrant
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:AmeliaHoldingIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Warrants to purchase percentage of equity				0.10%
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Delayed Draw), Senior Secured Loans, due 6/10/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember		mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,539
Fair value at the ending		$ 1,437		$ 1,539
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C ( Revolver), Senior Secured Loans, due 6/10/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember		mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 118
Fair value at the ending		$ 122		$ 118
Investment, Identifier [Axis]: American Broadband and Telecommunications Company L L C, Equity Securities, Warrants
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember		mrcc:AmericanBroadbandandTelecommunicationsCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 69
Fair value at the ending		$ 54		$ 69
Warrants to purchase percentage of equity		0.20%		0.20%
Investment, Identifier [Axis]: American Community Homes, Inc. ( Revolver), Senior Secured Loans Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities Due 12/18/2024, Warrants
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning			$ 264	$ 264
Net unrealized gain (loss)			$ (264)
Warrants to purchase percentage of equity			22.30%
Number of shares held		4,940
Investment, Identifier [Axis]: American Community Homes, Inc., Equity Securities, Common Stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held				4,940
Percentage of units held		4940.00%
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Acquisition Date 3/29/2019
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,694	$ 4,357	$ 4,357
PIK Interest (cost)		312	192
Net unrealized gain (loss)		(383)	(373)
Fair value at the ending		$ 3,623	$ 4,176	$ 3,694
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Five, Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,694
Fair value at the ending		$ 3,623		$ 3,694
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Acquisition Date 8/10/2018
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,996	$ 3,164	3,164
PIK Interest (cost)		168	104
Net unrealized gain (loss)		(207)	(1,012)
Fair value at the ending		$ 1,957	$ 2,256	$ 1,996
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Four, Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,996
Fair value at the ending		$ 1,957		$ 1,996
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Acquisition Date 7/22/2014
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 8,953	$ 10,457	10,457
PIK Interest (cost)		756	466
Net unrealized gain (loss)		(928)	(804)
Fair value at the ending		$ 8,781	10,119	$ 8,953
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, One, Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 8,953
Fair value at the ending		$ 8,781		$ 8,953
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Acquisition Date 12/30/2019
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 85	99	99
PIK Interest (cost)		8	4
Net unrealized gain (loss)		(10)	(7)
Fair value at the ending		$ 83	$ 96	$ 85
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Seven, Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 85
Fair value at the ending		$ 83		$ 85
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Acquisition Date 9/30/2019
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 17	$ 20	20
PIK Interest (cost)		1	1
Net unrealized gain (loss)		(1)	(1)
Fair value at the ending		$ 17	$ 20	$ 17
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Six, Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 17
Fair value at the ending		$ 17		$ 17
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Acquisition Date 5/24/2017
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 543	$ 634	634
PIK Interest (cost)		45	28
Net unrealized gain (loss)		(56)	(49)
Fair value at the ending		$ 532	$ 613	$ 543
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Three, Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 543
Fair value at the ending		$ 532		$ 543
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Acquisition Date 7/22/2014
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]	American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,258	$ 4,753	4,753
PIK Interest (cost)		489	325
Net unrealized gain (loss)		(476)	(373)
Fair value at the ending		$ 4,271	$ 4,705	$ 4,258
Investment, Identifier [Axis]: American Community Homes, Inc., Senior Secured Loans, Two, Due 12/31/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		American Community Homes, Inc. [ Member]		American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,258
Fair value at the ending		$ 4,271		$ 4,258
Investment, Identifier [Axis]: Analogic Corporation, Senior Secured Loans, due 6/24/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Aras Corporation ( Revolver), Senior Secured Loans, due 4/13/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ArasCorporationMember		mrcc:ArasCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 50
Fair value at the ending		$ 100		$ 50
Investment, Identifier [Axis]: Aras Corporation, Senior Secured Loans, due 4/13/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ArasCorporationMember		mrcc:ArasCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,167
Fair value at the ending		$ 2,202		$ 2,167
Investment, Identifier [Axis]: Arcstor Midco, LLC, Due 3/16/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ArcstorMidcoLLCMember		mrcc:ArcstorMidcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,122
Fair value at the ending		$ 3,434		$ 4,122
Investment, Identifier [Axis]: Ascent Midco, L L C ( Revolver), Senior Secured Loans Due 2/5/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Investment, Identifier [Axis]: Ascent Midco, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]	Ascent Midco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,969	$ 2,554	$ 2,554
Net unrealized gain (loss)		(43)	(936)
Fair value at the ending		$ 1,926	$ 1,618	$ 1,969
Number of shares held			2,032,258
Number of units held		2,032,258		2,032,258
Investment, Identifier [Axis]: Ascent Midco, L L C, Senior Secured Loans Due 2/5/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Ascent Midco, L L C [ Member]		Ascent Midco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 6,217	$ 6,392	$ 6,392
Sales and paydowns (cost)		(6,175)	(87)
Discount accretion		16	14
Net unrealized gain (loss)		$ (58)	(15)
Fair value at the ending			$ 6,304	$ 6,217
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 522
Fair value at the ending		$ 448		$ 522
Number of units held		297,197		297,197
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Five, due 7/3/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 399
Fair value at the ending		$ 396		$ 399
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Four, due 7/3/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 794
Fair value at the ending		$ 784		$ 794
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, One, due 7/3/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,915
Fair value at the ending		$ 1,891		$ 1,915
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Three, due 7/3/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 275
Fair value at the ending		$ 272		$ 275
Investment, Identifier [Axis]: Attom Intermediate Holdco, L L C, Senior Secured Loans, Two, due 7/3/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 467
Fair value at the ending		$ 461		$ 467
Investment, Identifier [Axis]: Attom Intermediate Holdco, LLC (Revolver), Senior Secured Loans, due 7/3/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AttomIntermediateHoldcoLLCMember		mrcc:AttomIntermediateHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 119
Investment, Identifier [Axis]: Avalara, Inc. (Revolver), Senior Secured Loans, due 10/19/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AvalaraInc.Member		mrcc:AvalaraInc.Member
Investment, Identifier [Axis]: Avalara, Inc. Senior Secured Loans, due 10/19/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:AvalaraInc.Member		mrcc:AvalaraInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,900
Fair value at the ending		$ 4,000		$ 3,900
Investment, Identifier [Axis]: Avison Young ( U S A) Inc., Senior Secured Loans, due 1/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BLSTOperatingCompanyLLCMember		mrcc:BLSTOperatingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 420
Fair value at the ending		$ 420		$ 420
Number of shares held		139,883
Number of units held				139,883
Investment, Identifier [Axis]: B L S T Operating Company, L L C, Senior Secured Loans, due 8/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BLSTOperatingCompanyLLCMember		mrcc:BLSTOperatingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 571
Fair value at the ending		581		$ 571
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Delayed Draw) , Senior Secured Loans, due 9/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings) ( Revolver), Senior Secured Loans, due 9/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		389
Fair value at the ending				$ 389
Investment, Identifier [Axis]: Bonterra, L L C (fka Cybergrants Holdings), Senior Secured Loans, due 9/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 12,898
Fair value at the ending				$ 12,898
Investment, Identifier [Axis]: Bonterra, LLC (Delayed Draw), Senior Secured Loans, Due 9/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Investment, Identifier [Axis]: Bonterra, LLC (Revolver), Senior Secured Loans, Due 9/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,030
Investment, Identifier [Axis]: Bonterra, LLC, Senior Secured Loans, Due 9/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BonterraLLCfkaCybergrantsHoldingsMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 13,153
Investment, Identifier [Axis]: Born To Run, L L C ( Delayed Draw) Senior Secured Loans, due 4/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:BornToRunLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 452
Fair value at the ending				$ 452
Investment, Identifier [Axis]: Born To Run, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BornToRunLLCMember		mrcc:BornToRunLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 233
Fair value at the ending		$ 55		$ 233
Number of shares held		269,438
Number of units held				269,438
Investment, Identifier [Axis]: Born To Run, L L C, Senior Secured Loans, due 4/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BornToRunLLCMember		mrcc:BornToRunLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,318
Fair value at the ending		$ 3,060		$ 3,318
Investment, Identifier [Axis]: Born To Run, LLC, Senior Secured Loans, Two, Due 4/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BornToRunLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 417
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp, Senior Secured Loans, due 2/12/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BrickellBayAcquisitionCorpMember		mrcc:BrickellBayAcquisitionCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,847
Fair value at the ending		1,868		$ 1,847
Investment, Identifier [Axis]: Brickell Bay Acquisition Corp., Senior Secured Loans, due 6/30/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:BrickellBayAcquisitionCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,630
Fair value at the ending				$ 4,630
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, One, due 11/5/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Bromford Industries Limited, Senior Secured Loans, Two, due 11/5/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Burroughs, Inc. ( Revolver), Senior Secured Loans, due 12/22/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:BurroughsInc.Member
Investment, Identifier [Axis]: Burroughs, Inc. (Revolver), Senior Secured Loans, due 12/22/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 795
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, One, due 12/22/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:BurroughsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 5,051
Investment, Identifier [Axis]: Burroughs, Inc., Senior Secured Loans, due 12/22/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:BurroughsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,201
Fair value at the ending				$ 5,201
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, One, due 4/10/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CHAHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,876
Investment, Identifier [Axis]: C H A Holdings, Inc, Senior Secured Loans, Two, due 4/10/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CHAHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 396
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC) (Revolver), Senior Secured Loans
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning			$ 550	$ 550
Purchases (cost)			92
Sales and paydowns (cost)			(470)
Net unrealized gain (loss)			165
Fair value at the ending			$ 337
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Equity Securities, Common Stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]	C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held		58,779	58,779
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Junior Secured Loans, One
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Junior Secured Loans, Two
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]
Investment, Identifier [Axis]: C Parent Holdings, LLC. (fka Curion Holdings, LLC), Senior Secured Loans
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]		C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 146	$ 4,561	$ 4,561
Sales and paydowns (cost)			(97)
Net unrealized gain (loss)		$ (146)	1,442
Fair value at the ending			5,906	$ 146
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, One, due 12/17/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CgiAutomatedManufacturingLlcMember		mrcc:CgiAutomatedManufacturingLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,975
Fair value at the ending		$ 3,856		$ 3,975
Investment, Identifier [Axis]: CGI Automated Manufacturing, LLC, Senior Secured Loans, Two, due 12/17/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCPShawAcquisitioncoLLCMember		mrcc:CgiAutomatedManufacturingLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,141
Fair value at the ending		$ 1,107		$ 1,141
Investment, Identifier [Axis]: Cadent, L L C ( Revolver), Senior Secured Loans, due 9/11/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CadentLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 92
Investment, Identifier [Axis]: Cadent, L L C, Senior Secured Loans, due 9/11/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CadentLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,229
Investment, Identifier [Axis]: Calabrio, Inc. ( Revolver), Senior Secured Loans, due 4/16/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CalabrioIncMember		mrcc:CalabrioIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 233
Fair value at the ending		$ 233		$ 233
Investment, Identifier [Axis]: Calabrio, Inc., Senior Secured Loans, due 4/16/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CalabrioIncMember		mrcc:CalabrioIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,379
Fair value at the ending		3,383		$ 3,379
Investment, Identifier [Axis]: California Pizza Kitchen, Inc., Equity Securities, Common units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:CaliforniaPizzaKitchenInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,266
Fair value at the ending				$ 1,266
Number of units held				78,699
Investment, Identifier [Axis]: Cano Health, L L C, Senior Secured Loans, due 11/23/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CanoHealthLLMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,657
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Delayed Draw), Senior Secured Loans, due 6/30/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CaravelAutismHealthLLCMember		mrcc:CaravelAutismHealthLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 173
Fair value at the ending		$ 1,335		$ 173
Investment, Identifier [Axis]: Caravel Autism Health, L L C ( Revolver), Senior Secured Loans, due 6/30/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CaravelAutismHealthLLCMember		mrcc:CaravelAutismHealthLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,048
Fair value at the ending		$ 471		$ 1,048
Investment, Identifier [Axis]: Caravel Autism Health, L L C, Senior Secured Loans, due 6/30/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CaravelAutismHealthLLCMember		mrcc:CaravelAutismHealthLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,808
Investment, Identifier [Axis]: Cassavant Holdings, L L C, Unitranche Secured Loans, due 9/8/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CassavantHoldingsLLCMember		mrcc:CassavantHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 7,436
Fair value at the ending		$ 7,447		$ 7,436
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Delayed Draw), Senior Secured Loans, due 4/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember		mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 337
Fair value at the ending		$ 286		$ 337
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C ( Revolver), Senior Secured Loans, due 4/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember		mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 719
Fair value at the ending		$ 453		$ 719
Investment, Identifier [Axis]: Centaur ( Palm Beach) Owner L L C and Panther National Golf Club L L C, Senior Secured Loans, due 4/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember		mrcc:CentaurPalmBeachOwnerLLCandPantherNationalGolfClubLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,296
Fair value at the ending		$ 2,798		$ 3,296
Investment, Identifier [Axis]: Chess.com, L L C ( Revolver), Senior Secured Loans, due 12/31/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Chess.comLLCMember		mrcc:Chess.comLLCMember
Investment, Identifier [Axis]: Chess.com, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Chess.comLLCMember		mrcc:Chess.comLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 50
Fair value at the ending		$ 49		$ 50
Number of units held		2		2
Investment, Identifier [Axis]: Chess.com, L L C, Senior Secured Loans, due 12/31/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Chess.comLLCMember		mrcc:Chess.comLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,866
Fair value at the ending		$ 5,851		$ 5,866
Investment, Identifier [Axis]: Corel Inc., Senior Secured Loans, due 7/2/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CorelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 3,196
Investment, Identifier [Axis]: Crownpeak Technology Inc. (Revolver) Senior Secured Loans, Due 2/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember		mrcc:CrownpeakTechnologyIncMember
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Four, Due 2/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember		mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,333
Fair value at the ending		$ 3,333		$ 3,333
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans One, Due 2/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember		mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,000
Fair value at the ending		$ 4,000		$ 4,000
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Three, Due 2/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember		mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 60
Fair value at the ending		$ 60		$ 60
Investment, Identifier [Axis]: Crownpeak Technology Inc. Senior Secured Loans Two, Due 2/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:CrownpeakTechnologyIncMember		mrcc:CrownpeakTechnologyIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,273
Fair value at the ending		$ 1,273		$ 1,273
Investment, Identifier [Axis]: Curion Holdings, L L C, Equity Securities, Common stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				Curion Holdings, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held				58,779
Investment, Identifier [Axis]: D S Parent, Inc., Senior Secured Loans, due 12/8/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Destination Media, Inc. ( Revolver), Senior Secured Loans, due 4/7/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc. (Delayed Draw), Senior Secured Loans, due 6/21/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc. (Revolver), Senior Secured Loans, due 6/21/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Investment, Identifier [Axis]: Destination Media, Inc., Senior Secured Loans, due 4/7/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:DestinationMediaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 377
Fair value at the ending				$ 377
Investment, Identifier [Axis]: Destination Media, Inc., Senior Secured Loans, due 6/21/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DestinationMediaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 965
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, One, Class A-1 units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DoradoAcquisitionIncMember		mrcc:DoradoAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 215
Fair value at the ending		$ 209		$ 215
Number of units held		189,922		189,922
Investment, Identifier [Axis]: Dorado Acquisition, Inc, Equity Securities, Two, Class A-2 units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DoradoAcquisitionIncMember		mrcc:DoradoAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 224
Fair value at the ending		$ 305		$ 224
Number of units held		189,922		189,922
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Delayed Draw) , Senior Secured Loans, due 6/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:DoradoAcquisitionInc.Member
Investment, Identifier [Axis]: Dorado Acquisition, Inc. ( Revolver) , Senior Secured Loans, due 6/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DoradoAcquisitionInc.Member		mrcc:DoradoAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 596
Fair value at the ending				$ 596
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, One, due 6/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DoradoAcquisitionInc.Member		mrcc:DoradoAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,928
Fair value at the ending		$ 4,819		$ 4,928
Investment, Identifier [Axis]: Dorado Acquisition, Inc., Senior Secured Loans, Two, Due 6/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DoradoAcquisitionInc.Member		mrcc:DoradoAcquisitionInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,074
Fair value at the ending		$ 3,994		$ 4,074
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Delayed Draw), Senior Secured Loans, due 9/1/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DrawbridgePartnersLlcMember		mrcc:DrawbridgePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 102
Fair value at the ending		$ 288		$ 102
Investment, Identifier [Axis]: Drawbridge Partners, LLC (Revolver), Senior Secured Loans, due 9/1/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DrawbridgePartnersLlcMember		mrcc:DrawbridgePartnersLlcMember
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Equity Securities, Class A Units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DrawbridgePartnersLlcMember		mrcc:DrawbridgePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 126
Fair value at the ending		$ 123		$ 126
Number of units held		130,433		130,433
Investment, Identifier [Axis]: Drawbridge Partners, LLC, Senior Secured Loans, due 9/1/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DrawbridgePartnersLlcMember		mrcc:DrawbridgePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,971
Fair value at the ending		$ 2,973		$ 2,971
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, One, due 10/1/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,610
Investment, Identifier [Axis]: Dresser Utility Solutions, L L C (fka N G S U S Finco, L L C), Senior Secured Loans, Two, due 10/1/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:DresserUtilitySolutionsLLCfkaNGSUSFincoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 238
Investment, Identifier [Axis]: Drilling Info Holdings, Inc., Senior Secured Loans, due 7/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Education Corporation of America, Equity Securities, Series G Preferred Stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EducationCorporationofAmericaMember		mrcc:EducationCorporationofAmericaMember
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held		8,333		8,333
Investment, Identifier [Axis]: Education Corporation of America, Junior Secured Loans
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EducationCorporationofAmericaMember		mrcc:EducationCorporationofAmericaMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,882
Fair value at the ending		$ 2,039		$ 1,882
Investment, Identifier [Axis]: Eliassen Group, L L C ( Delayed Draw), Senior Secured Loans, due 4/14/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EliassenGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 108
Investment, Identifier [Axis]: Eliassen Group, L L C, Senior Secured Loans, due 4/14/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EliassenGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 3,172
Investment, Identifier [Axis]: Engage2 Excel, Inc. ( Revolver), Senior Secured Loans, due 3/7/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Engage2 Excel, Inc. (Revolver), Senior Secured Loans, One, due 12/31/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Engage2ExcelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 550
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, One, due 12/31/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Engage2ExcelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,270
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, One, due 3/7/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, Two, due 12/31/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:Engage2ExcelIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 770
Investment, Identifier [Axis]: Engage2 Excel, Inc., Senior Secured Loans, Two,due 3/7/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Equine Network, L L C, (Delayed Draw), Senior Secured Loans, due 12/31/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:EquineNetworkLLCMember
Investment, Identifier [Axis]: Equine Network, L L C, (Revolver), Senior Secured Loans, due 12/31/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 127
Fair value at the ending				$ 127
Investment, Identifier [Axis]: Equine Network, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:EquineNetworkLLCMember		mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 109
Fair value at the ending		$ 72		$ 109
Number of units held		108		108
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, One, due 12/31/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,709
Fair value at the ending				$ 1,709
Investment, Identifier [Axis]: Equine Network, L L C, Senior Secured Loans, Two, due 12/31/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:EquineNetworkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 775
Fair value at the ending				$ 775
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc. ( Revolver), Senior Secured Loans, due 4/28/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExcelFitnessHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 330
Investment, Identifier [Axis]: Excel Fitness Holdings, Inc., Senior Secured Loans, due 4/27/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExcelFitnessHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,038
Investment, Identifier [Axis]: Express Wash Acquisition Company, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 118
Fair value at the ending		$ 107		$ 118
Number of shares held		121,311
Number of units held				121,311
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC (Revolver), Senior Secured Loans, due 7/14/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 208
Fair value at the ending		$ 209		$ 208
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, One, Due 7/14/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 8,119
Fair value at the ending		$ 8,119		$ 8,119
Investment, Identifier [Axis]: Express Wash Acquisition Company, LLC, Senior Secured Loans, Two, Due 7/14/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ExpressWashAcquisitionCompanyLLCMember		mrcc:ExpressWashAcquisitionCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,521
Fair value at the ending		$ 1,521		$ 1,521
Investment, Identifier [Axis]: Familia Dental Group Holdings, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Familia Dental Group Holdings, LLC		Familia Dental Group Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,625	1,919	$ 1,919
Purchases (cost)		60	183
Net unrealized gain (loss)		(244)	653
Fair value at the ending		$ 2,441	$ 2,755	$ 2,625
Number of shares held		1,194
Number of units held		1,194	1,158	1,176
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Junior Secured Loans, due 6/28/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FloridaEastCoastIndustriesLLCMember		mrcc:FloridaEastCoastIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,784
Fair value at the ending		813		$ 1,784
Investment, Identifier [Axis]: Florida East Coast Industries, L L C, Senior Secured Loans, due 6/28/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:FloridaEastCoastIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		619
Fair value at the ending				$ 619
Investment, Identifier [Axis]: Forman Mills, Inc, Equity Securities, Warrants
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:FormanMillsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		155
Fair value at the ending				$ 155
Warrants to purchase percentage of equity				2.60%
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, One, due 4/30/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:FormanMillsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,253
Fair value at the ending				$ 1,253
Investment, Identifier [Axis]: Forman Mills, Inc, Senior Secured Loans, Two, due 4/30/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:FormanMillsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 6,698
Fair value at the ending				$ 6,698
Investment, Identifier [Axis]: Forman Mills, Inc., Senior Secured Loans, due 6/20/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:FormanMillsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 966
Investment, Identifier [Axis]: GC Champion Acquisition LLC (Delayed Draw), Senior Notes, Due 8/18/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:GCChampionAcquisitionLLCMember
Investment, Identifier [Axis]: GC Champion Acquisition LLC, Senior Notes, Due 8/18/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:GCChampionAcquisitionLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,503
Fair value at the ending				$ 2,503
Investment, Identifier [Axis]: GC Champion Acquisition LLC, Senior Notes, One, Due 8/18/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:GCChampionAcquisitionLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,535
Investment, Identifier [Axis]: GC Champion Acquisition LLC, Senior Notes, Two, Due 8/18/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:GCChampionAcquisitionLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 704
Investment, Identifier [Axis]: H A H Group Holding Company L L C, Senior Secured Loans, due 10/29/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HAHGroupHoldingCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,902
Investment, Identifier [Axis]: H A L O Buyer, Inc., Senior Secured Loans, due 6/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HALOBuyerIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,290
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans , Two
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember	mrcc:HFZCapitalGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,805	$ 5,420	$ 5,420
Net unrealized gain (loss)		192	191
Fair value at the ending		$ 5,997	5,611	$ 5,805
Investment, Identifier [Axis]: H F Z Capital Group L L C, Senior Secured Loans, One
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HFZCapitalGroupLLCMember		mrcc:HFZCapitalGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 16,159	15,084	$ 15,084
Net unrealized gain (loss)		532	533
Fair value at the ending		$ 16,691	$ 15,617	$ 16,159
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc. ( Revolver), Senior Secured Loans, due 7/9/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HS4AcquisitioncoIncMember		mrcc:HS4AcquisitioncoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 407
Fair value at the ending		$ 557		$ 407
Investment, Identifier [Axis]: H S4 Acquisitionco, Inc., Senior Secured Loans, due 7/9/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HS4AcquisitioncoIncMember		mrcc:HS4AcquisitioncoIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 9,855
Fair value at the ending		$ 9,800		$ 9,855
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, One, due 12/13/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Harbour Benefit Holdings, Inc., Senior Secured Loans, Two, due 12/13/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Hastings Manufacturing Company (Revolver), Senior Secured Loans, Due 12/31/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HastingsManufacturingCompanyMember
Investment, Identifier [Axis]: Hastings Manufacturing Company , Senior Secured Loans, One, Due 12/31/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HastingsManufacturingCompanyMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,933
Investment, Identifier [Axis]: Hastings Manufacturing Company , Senior Secured Loans, Two, Due 12/31/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:HastingsManufacturingCompanyMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 685
Investment, Identifier [Axis]: Hastings Manufacturing Company, Senior Secured Loans, due 4/24/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:HastingsManufacturingCompanyMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,026
Fair value at the ending				$ 2,026
Investment, Identifier [Axis]: I D I G Parent, L L C, Equity Securities, Common stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		I D I G Parent, L L C [ Member]		I D I G Parent, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 324
Fair value at the ending		$ 293		$ 324
Number of shares held				245,958
Number of units held		245,958
Investment, Identifier [Axis]: I N H Buyer, Inc., Senior Secured Loans, due 6/28/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:INHBuyerInc.Member		mrcc:INHBuyerInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,832
Fair value at the ending		$ 2,898		$ 2,832
Investment, Identifier [Axis]: In Mobi Pte, Ltd, Media: Equity Securities, due 9/18/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:InMobiPteLtdMember		mrcc:InMobiPteLtdMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,816
Fair value at the ending		$ 2,213		$ 1,816
Warrants to purchase percentage of equity		2.80%		2.80%
Investment, Identifier [Axis]: Independence Buyer, Inc, Senior Secured Loans, due 8/3/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:IndependenceBuyerInc.Member		mrcc:IndependenceBuyerInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,866
Fair value at the ending		$ 5,437		$ 5,866
Investment, Identifier [Axis]: Independence Buyer, Inc. ( Revolver), Senior Secured Loans, due 8/3/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:IndependenceBuyerInc.Member		mrcc:IndependenceBuyerInc.Member
Investment, Identifier [Axis]: Independence Buyer, Inc., Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:IndependenceBuyerInc.Member		mrcc:IndependenceBuyerInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 102
Fair value at the ending		$ 79		$ 102
Number of units held		81		81
Investment, Identifier [Axis]: Intermedia Holdings, Inc., Senior Secured Loans, due 7/21/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:IntermediaHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,427
Investment, Identifier [Axis]: International Textile Group, Inc., Senior Secured Loans, due 5/1/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: J2 B W A Funding L L C, Equity Securities
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:J2BWAFundingLLCMember		mrcc:J2BWAFundingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 21
Investment, Identifier [Axis]: J2 BWA Funding LLC (Delayed Draw), Senior Notes, Due 12/24/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:J2BWAFundingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,298
Fair value at the ending				$ 1,298
Investment, Identifier [Axis]: J2 BWA Funding LLC (Revolver), Senior Secured Loans, Due 12/24/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:J2BWAFundingLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,482
Investment, Identifier [Axis]: KL Moon Acquisition LLC Common Units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KlMoonAcquisitionLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 544
Number of units held		0.1
Investment, Identifier [Axis]: KL Moon Acquisition, LLC (Delayed Draw), Senior Secured Loans, Due 2/1/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KlMoonAcquisitionLlcMember
Investment, Identifier [Axis]: KL Moon Acquisition, LLC (Revolver), Senior Secured Loans, Due 2/1/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KlMoonAcquisitionLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 244
Investment, Identifier [Axis]: KL Moon Acquisition, LLC, Senior Secured Loans, Due 2/1/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KlMoonAcquisitionLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 5,000
Investment, Identifier [Axis]: Kar Wash Holdings LLC Equity Securities Series A Preferred Stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 11
Number of shares held		8,619
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 2/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KarWashHoldingsLLCMember		mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,782
Fair value at the ending		$ 1,774		$ 1,782
Investment, Identifier [Axis]: Kar Wash Holdings, L L C ( Revolver), Senior Secured Loans, due 2/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KarWashHoldingsLLCMember		mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 303
Fair value at the ending		$ 455		$ 303
Investment, Identifier [Axis]: Kar Wash Holdings, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KarWashHoldingsLLCMember		mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 111
Fair value at the ending		$ 75		$ 111
Number of shares held		99,807
Number of units held				99,807
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, One, due 2/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KarWashHoldingsLLCMember		mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,585
Fair value at the ending		$ 1,577		$ 1,585
Investment, Identifier [Axis]: Kar Wash Holdings, LLC, Senior Secured Loans, Two, due 2/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KarWashHoldingsLLCMember		mrcc:KarWashHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,135
Fair value at the ending		$ 1,129		$ 1,135
Investment, Identifier [Axis]: Keystone Purchaser, L L C, Senior Secured Loans, due 5/7/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KeystonePurchaserLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,893
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), Senior Secured Loans, One, Due 12/11/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KingsleyGatePartnersLlcMember		mrcc:KingsleyGatePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 191
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Delayed Draw), Senior Secured Loans, Two, Due 12/11/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KingsleyGatePartnersLlcMember		mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC (Revolver), Senior Secured Loans, Due 12/11/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KingsleyGatePartnersLlcMember		mrcc:KingsleyGatePartnersLlcMember
Investment, Identifier [Axis]: Kingsley Gate Partners, LLC, , Senior Secured Loans, Due 12/11/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:KingsleyGatePartnersLlcMember		mrcc:KingsleyGatePartnersLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 588
Fair value at the ending		$ 596		$ 588
Investment, Identifier [Axis]: L S C S Holdings, Inc., Senior Secured Loans, due 12/15/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LSCSHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,780
Investment, Identifier [Axis]: L V F Holdings, Inc. ( Revolver), Senior Secured Loans, due 6/10/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LXJTIntermediateHoldingsIncMember		mrcc:LVFHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 152
Fair value at the ending		$ 134		$ 152
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, ( Delayed Draw) due 6/10/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:LVFHoldingsIncMember
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, One, due 6/10/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LVFHoldingsIncMember		mrcc:LVFHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,437
Fair value at the ending		$ 1,433		$ 1,437
Investment, Identifier [Axis]: L V F Holdings, Inc., Senior Secured Loans, Two, due 6/10/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LVFHoldingsIncMember		mrcc:LVFHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,375
Fair value at the ending		$ 1,372		$ 1,375
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc. ( Revolver), Senior Secured Loans, due 3/11/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LXJTIntermediateHoldingsIncMember		mrcc:LXJTIntermediateHoldingsIncMember
Investment, Identifier [Axis]: L X/ J T Intermediate Holdings, Inc., Senior Secured Loans, due 3/11/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LXJTIntermediateHoldingsIncMember		mrcc:LXJTIntermediateHoldingsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,394
Fair value at the ending		$ 5,380		$ 5,394
Investment, Identifier [Axis]: Laseraway Intermediate Holdings I I, L L C, Senior Secured Loans, due 10/14/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LaserawayIntermediateHoldingsIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,153
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Delayed Draw), Senior Secured Loans, due 8/2/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:LiftedTrucksHoldingsLLCMember
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C ( Revolver), Senior Secured Loans, due 8/2/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftedTrucksHoldingsLLCMember		mrcc:LiftedTrucksHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 220
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftedTrucksHoldingsLLCMember		mrcc:LiftedTrucksHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 78
Fair value at the ending		$ 92		$ 78
Number of shares held		111,111
Number of units held				111,111
Investment, Identifier [Axis]: Lifted Trucks Holdings, L L C, Senior Secured Loans, due 8/2/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftedTrucksHoldingsLLCMember		mrcc:LiftedTrucksHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 6,840
Fair value at the ending		$ 6,812		$ 6,840
Investment, Identifier [Axis]: Liftforward SPV II, LLC, Senior Secured Loans, Due 9/30/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LiftforwardSPVIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 383
Investment, Identifier [Axis]: Liftforward SPV II, LLC, Senior Secured Loans, due 3/31/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:LiftforwardSPVIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 403
Fair value at the ending				$ 403
Investment, Identifier [Axis]: Lightbox Intermediate, L. P., Senior Secured Loans, due 5/11/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:LightboxIntermediateL.PMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,680
Investment, Identifier [Axis]: Luxury Optical Holdings Co., Equity Securities
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:LuxuryOpticalHoldingsCo.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 209
Fair value at the ending				$ 209
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C ( Delayed Draw), Senior Secured Loans Due 1/26/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,000	$ 850	$ 850
PIK Interest (cost)			70
Fair value at the ending		$ 2,762	$ 920	$ 1,000
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securites
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCAssetManagementCorporateLLCMember		mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,291
Fair value at the ending		$ 1,413		$ 1,291
Percentage of equity interest				15.90%
Percentage of units held		15.90%
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Equity Securities
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCAssetManagementCorporateLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,291	$ 644	$ 644
Net unrealized gain (loss)		122	(205)
Fair value at the ending		$ 1,413	$ 439	$ 1,291
Percentage of equity interest		15.90%	15.90%
Investment, Identifier [Axis]: M C Asset Management ( Corporate), L L C, Senior Secured Loans Due 1/26/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCAssetManagementCorporateLLCMember	mrcc:HFZCapitalGroupLLCMember	mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 8,421	$ 7,154	$ 7,154
PIK Interest (cost)		839	590
Fair value at the ending		$ 9,260	7,744	$ 8,421
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C ( Revolver), Senior Secured Loans, due 11/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCPShawAcquisitioncoLLCMember		mrcc:MCPShawAcquisitioncoLLCMember
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C , Equity Securities, Class A-2 units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCPShawAcquisitioncoLLCMember		mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 204
Fair value at the ending		$ 388		$ 204
Number of units held		118,906		118,906
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, One, due 11/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCPShawAcquisitioncoLLCMember		mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 9,736
Fair value at the ending		$ 970		$ 9,736
Investment, Identifier [Axis]: M C P Shaw Acquisitionco, L L C, Senior Secured Loans, Two, due 11/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCPShawAcquisitioncoLLCMember		mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,977
Fair value at the ending		$ 2,950		$ 2,977
Investment, Identifier [Axis]: M R C C Senior Loan Fund I, L L C, Equity Securities
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Controlled affiliate company investments		Controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		MRCC Senior Loan Fund I, LLC		MRCC Senior Loan Fund I, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 35,509	41,125	$ 41,125
Purchases (cost)			500
Net unrealized gain (loss)		(964)	(4,074)
Fair value at the ending		34,545	$ 37,551	$ 35,509
Percentage of equity interest				50.00%
Investment, Identifier [Axis]: M V Receivables I I, L L C ( Delayed Draw), Senior Secured Loans, due 7/29/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MVReceivablesIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 7,968
Fair value at the ending				$ 7,968
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Common units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MVReceivablesIILLCMember		mrcc:MVReceivablesIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,154
Fair value at the ending				$ 1,154
Warrants to purchase percentage of equity				0.80%
Number of units held		1,458		1,458
Investment, Identifier [Axis]: M V Receivables I I, L L C, Equity Securities, Due 7/28/2031, Warrants
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MVReceivablesIILLCMember		mrcc:MVReceivablesIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,655
Fair value at the ending				$ 1,655
Warrants to purchase percentage of equity		0.80%
Investment, Identifier [Axis]: M V Receivables I I, L L C, Senior Secured Loans, due 7/29/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MVReceivablesIILLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 9,930
Investment, Identifier [Axis]: MC Asset Management (Corporate), LLC, Senior Secured Loans, Two, Due 1/26/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,000
Purchases (cost)		1,586
PIK Interest (cost)		176
Fair value at the ending		$ 2,762		$ 1,000
Investment, Identifier [Axis]: MCP Shaw Acquisitionco, LLC, Senior Secured Loans, Three, due 11/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MCPShawAcquisitioncoLLCMember		mrcc:MCPShawAcquisitioncoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 979
Fair value at the ending		$ 9,648		$ 979
Investment, Identifier [Axis]: MEI Buyer LLC (Delayed Draw), Senior Secured Loans, due 6/29/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MeiBuyerLlcMember
Investment, Identifier [Axis]: MEI Buyer LLC (Revolver), Senior Secured Loans, due 6/29/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MeiBuyerLlcMember
Investment, Identifier [Axis]: MEI Buyer LLC, Equity Securities, Common Stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MeiBuyerLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 155
Number of shares held		155
Investment, Identifier [Axis]: MEI Buyer LLC, Senior Secured Loans, due 6/29/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MeiBuyerLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,940
Investment, Identifier [Axis]: MRCC Senior Loan Fund I, LLC, Equity Securities (50.0% of the Equity Interests)
Transactions with Affiliated Companies, Fair value Roll Forward
Percentage of equity interest		50.00%
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Delayed Draw), Senior Secured Loans, due 1/7/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Mac Queen Equipment, L L C ( Revolver), Senior Secured Loans, due 1/7/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Mac Queen Equipment, L L C, Senior Secured Loans, due 1/7/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Mammoth Holdings, LLC (Revolver), Senior Secured Loans, Due, 10/16/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember		mrcc:MammothHoldingsLLCMember
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Due 10/16/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 13,784
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Four, due 10/16/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,630
Fair value at the ending				$ 1,630
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, One, due 10/16/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,917
Fair value at the ending				$ 1,917
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Three, due 10/16/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		6,282
Fair value at the ending				$ 6,282
Investment, Identifier [Axis]: Mammoth Holdings, LLC, Senior Secured Loans, Two, due 10/16/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MammothHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		4,025
Fair value at the ending				$ 4,025
Investment, Identifier [Axis]: Mark Logic Corporation ( Revolver), Senior Secured Loans, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MarkLogicCorporationMember
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Four, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		213
Fair value at the ending				$ 213
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, One, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		3,414
Fair value at the ending				$ 3,414
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Three, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		2,656
Fair value at the ending				$ 2,656
Investment, Identifier [Axis]: Mark Logic Corporation, Senior Secured Loans, Two, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		318
Fair value at the ending				$ 318
Investment, Identifier [Axis]: MarkLogic Corporation, Equity Securities, Class A Units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MarkLogicCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 426
Fair value at the ending				$ 426
Number of units held				290,239
Investment, Identifier [Axis]: Mavenir Systems, Inc., Senior Secured Loans, due 8/18/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MavenirSystemsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,195
Investment, Identifier [Axis]: Mc Kissock Investment Holdings, L L C, Senior Secured Loans, due 3/9/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:McKissockInvestmentHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,395
Investment, Identifier [Axis]: Medallia, Inc, Senior Secured Loans, due 10/27/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MedalliaIncMember		mrcc:MedalliaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,041
Fair value at the ending		$ 2,112		$ 2,041
Investment, Identifier [Axis]: Mindbody, Inc. ( Revolver) (f), Senior Secured Loans, due 2/14/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MindbodyIncMember		mrcc:MedalliaIncMember
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, One, due 2/14/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MindbodyIncMember		mrcc:MedalliaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 6,526
Fair value at the ending		$ 6,533		$ 6,526
Investment, Identifier [Axis]: Mindbody, Inc., Senior Secured Loans, Two, due 2/14/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MindbodyIncMember		mrcc:MedalliaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 673
Fair value at the ending		$ 673		$ 673
Investment, Identifier [Axis]: Minotaur Acquisition, Inc., Senior Secured Loans, due 3/27/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Mnine Holdings, Inc (Revolver), Senior Secured Loans, Due 12/30/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 518
Investment, Identifier [Axis]: Mnine Holdings, Inc, Senior Secured Loans, Due 12/30/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,492
Fair value at the ending				$ 5,492
Investment, Identifier [Axis]: Mnine Holdings, Inc, Senior Secured Loans, Due 12/30/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 5,859
Investment, Identifier [Axis]: Mnine Holdings, Inc. (Revolver), Senior Secured Loans, due 12/30/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Mnine Holdings, Inc [ Member]		Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 214
Purchases (cost)		293
PIK Interest (cost)		11
Fair value at the ending		$ 518		$ 214
Investment, Identifier [Axis]: Mnine Holdings, Inc., Equity Securities, Class B units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]	Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Number of units held		6,400	6,400	6,400
Investment, Identifier [Axis]: Mnine Holdings, Inc., Senior Secured Loans Due 12/30/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,492	$ 5,771	$ 5,771
PIK Interest (cost)		367	137
Discount accretion		10	9
Net unrealized gain (loss)		(10)	(9)
Fair value at the ending		$ 5,859	5,908	$ 5,492
Investment, Identifier [Axis]: Money Lion, Inc. ( Delayed Draw), Junior Secured Loans, due 3/24/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MoneyLionIncMember
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 10/16/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MoneyLionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,126
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 3/24/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:MoneyLionIncMember		mrcc:MoneyLionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,165
Fair value at the ending		5,256		$ 5,165
Investment, Identifier [Axis]: Money Lion, Inc., Junior Secured Loans, due 5/1/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MoneyLionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,498
Fair value at the ending				$ 1,498
Investment, Identifier [Axis]: N C B P Property, L L C, Senior Secured Loans, due 12/16/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:NCBPPropertyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,955
Fair value at the ending				$ 1,955
Investment, Identifier [Axis]: N E C B Collections, L L C ( Revolver), Senior Secured Loans
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		N E C B Collections, L L C [ Member]		N E C B Collections, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 382	632	$ 632
Net unrealized gain (loss)		44	(117)
Fair value at the ending		$ 426	$ 515	$ 382
Investment, Identifier [Axis]: N E C B Collections, L L C, Equity Securities
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]	N E C B Collections, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Percentage of units held		20.80%	20.80%	20.80%
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Delayed Draw), Senior Secured Loans, Due 10/4/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NqPeProjectColosseumMidcoInc.Member		mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc. (Revolver), Senior Secured Loans, Due 10/4/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NqPeProjectColosseumMidcoInc.Member		mrcc:NqPeProjectColosseumMidcoInc.Member
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Equity Securities, Common Units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NqPeProjectColosseumMidcoInc.Member		mrcc:NqPeProjectColosseumMidcoInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 327
Fair value at the ending		$ 364		$ 327
Number of units held		327,133		327,133
Investment, Identifier [Axis]: NQ PE Project Colosseum Midco Inc., Senior Secured Loans, Due 10/4/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NqPeProjectColosseumMidcoInc.Member		mrcc:NqPeProjectColosseumMidcoInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,430
Fair value at the ending		$ 3,515		$ 3,430
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, One, Due 8/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,039
Fair value at the ending		$ 3,979		$ 4,039
Investment, Identifier [Axis]: Nations Benefits L L C, Senior Secured Loans, Two, Due 8/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,813
Fair value at the ending		$ 4,742		$ 4,813
Investment, Identifier [Axis]: Nations Benefits LLC Delayed Draw, Senior Secured Loans Due 8/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 961
Fair value at the ending		$ 5,135		$ 961
Investment, Identifier [Axis]: Nations Benefits, L L C (Revolver), Senior Secured Loans, Due 8/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 889
Fair value at the ending		$ 889		$ 889
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, One, Series B units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 934
Fair value at the ending		$ 711		$ 934
Number of units held		116,460		116,460
Investment, Identifier [Axis]: Nations Benefits, L L C, Equity Securities, Two, common units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NationsBenefitsLLCMember		mrcc:NationsBenefitsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 66
Fair value at the ending				$ 66
Number of units held		106,667		106,667
Investment, Identifier [Axis]: Natus Medical Incorporated, Senior Secured Loans, due 7/20/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NatusMedicalIncorporatedMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,577
Investment, Identifier [Axis]: Nearly Natural Inc. Senior Secured Loans One due 3/29/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 5,965
Investment, Identifier [Axis]: Nearly Natural Inc., Senior Secured Loans, Four, due 3/29/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,683
Investment, Identifier [Axis]: Nearly Natural Inc., Senior Secured Loans, Three, due 3/29/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,809
Investment, Identifier [Axis]: Nearly Natural Inc., Senior Secured Loans, Two, due 3/29/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,545
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, One, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember		mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Number of units held		152,174		152,174
Investment, Identifier [Axis]: Nearly Natural, Inc, Equity Securities, Two, Class A A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalIncMember		mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Number of units held		61,087		61,087
Investment, Identifier [Axis]: Nearly Natural, Inc. (Revolver), Senior Secured Loans, due 3/29/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NearlyNaturalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,345
Investment, Identifier [Axis]: Nearly Natural, Inc.( Revolver), Senior Secured loans, due 12/15/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		2,241
Fair value at the ending				$ 2,241
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Four, due 12/15/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,672
Fair value at the ending				$ 1,672
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, One, due 12/15/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		5,931
Fair value at the ending				$ 5,931
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Three, due 12/15/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		2,787
Fair value at the ending				$ 2,787
Investment, Identifier [Axis]: Nearly Natural, Inc., Senior Secured loans, Two, due 12/15/2022
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:NearlyNaturalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,534
Fair value at the ending				$ 1,534
Investment, Identifier [Axis]: Newforma, Inc. ( Revolver) (f), Senior Secured Loans, due 3/31/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MedalliaIncMember
Investment, Identifier [Axis]: Newforma, Inc., Senior Secured Loans, due 3/31/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:MedalliaIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 938
Fair value at the ending				$ 938
Investment, Identifier [Axis]: North Haven Spartan U S Holdco, L L C, Senior Secured Loans, due 6/6/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenSpartanUSHoldcoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,228
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Delayed Draw), Senior Secured Loans, due, 10/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenUSHCAcquisitionIncMember		mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,505
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc. ( Revolver), Senior Secured Loans, due, 10/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenUSHCAcquisitionIncMember		mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 187
Fair value at the ending		$ 2,379		$ 187
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, One, 10/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenUSHCAcquisitionIncMember		mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,448
Fair value at the ending		$ 305		$ 2,448
Investment, Identifier [Axis]: North Haven U S H C Acquisition, Inc., Senior Secured Loans, due, Two, 10/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenUSHCAcquisitionIncMember		mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,575
Fair value at the ending				$ 2,575
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Four, due 10/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenUSHCAcquisitionIncMember		mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,433
Fair value at the ending		$ 689		$ 1,433
Investment, Identifier [Axis]: North Haven USHC Acquisition, Inc, Senior Secured Loans, Three, due 10/30/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:NorthHavenUSHCAcquisitionIncMember		mrcc:NorthHavenUSHCAcquisitionIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 709
Fair value at the ending		1,392		$ 709
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, One, due 6/29/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:OceanaAustralianFixedIncomeTrustMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		3,084
Fair value at the ending				$ 3,084
Investment, Identifier [Axis]: Oceana Australian Fixed Income Trust, Senior Secured Loans, Two, due 2/25/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:OceanaAustralianFixedIncomeTrustMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 7,321
Fair value at the ending				$ 7,321
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, One, due 6/22/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Offen, Inc., Senior Secured Loans, Two, due 6/22/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Onit, Inc., Unitranche Secured Loans, due 5/2/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:OnitInc.Member		mrcc:OnitInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,663
Fair value at the ending		$ 1,678		$ 1,663
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, One, due 10/21/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Three, due 10/21/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Orbit Purchaser L L C, Senior Secured Loans, Two, due 10/21/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Output Services Group Inc. Senior Secured Loans Due 6/29/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Output Services Group, Inc., Senior Secured Loans, due 3/27/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:OutputServicesGroupIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,311
Investment, Identifier [Axis]: P H Beauty Holdings I I I, I N C., Senior Secured Loans, due 9/26/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Four, Preferred units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PKSHoldingsLLCMember		mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 46
Fair value at the ending		$ 40		$ 46
Number of shares held		916
Number of units held				916
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, One, Preferred units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PKSHoldingsLLCMember		mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 298
Fair value at the ending		$ 256		$ 298
Number of shares held		5,680
Number of units held				5,680
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Three, Preferred units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PKSHoldingsLLCMember		mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 7
Fair value at the ending		$ 6		$ 7
Number of shares held		132
Number of units held				132
Investment, Identifier [Axis]: P K S Holdings, L L C, Equity Securities, Two, Preferred units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PKSHoldingsLLCMember		mrcc:PKSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 46
Fair value at the ending		$ 40		$ 46
Number of shares held		5,714
Number of units held				5,714
Investment, Identifier [Axis]: P V H C Holding Corp, Senior Secured Loans, due 8/5/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Panda Acquisition, LLC, Senior Secured Loans, due 10/18/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PandaAcquisitionLlcMember		mrcc:PandaAcquisitionLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,690
Fair value at the ending		$ 3,722		$ 3,690
Investment, Identifier [Axis]: Paragon Healthcare Inc. Senior Secured Loan Due 1/19/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ParagonHealthcareIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,094
Investment, Identifier [Axis]: Paragon HealthcareInc. Delayed Draw Senior Secured Loans due 1/19/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Paragon HealthcareInc. Revolver Senior Secured Loan Due 1/19/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ParagonHealthcareIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 24
Investment, Identifier [Axis]: Paragon HealthcareInc., Senior Secured Loan, Two, Due 1/19/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ParagonHealthcareIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 361
Investment, Identifier [Axis]: Phoenix Chemical Holding Company LLC (fka Polymer Solutions Group), Senior Secured Loan due 6/15/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Five, due 12/28/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 704
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Four, due 12/28/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulInc.Member		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 878
Fair value at the ending		$ 880		$ 878
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, One, due 12/28/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulInc.Member		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 9,443
Fair value at the ending		$ 9,462		$ 9,443
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, One, due 12/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Three, due 12/28/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulInc.Member		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,318
Fair value at the ending		$ 1,320		$ 1,318
Investment, Identifier [Axis]: Planful, Inc, Senior Secured Loans, Two, due 12/28/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulInc.Member		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 527
Fair value at the ending		$ 528		$ 527
Investment, Identifier [Axis]: Planful, Inc. ( Revolver), Senior Secured Loans, due 12/28/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulInc.Member		mrcc:PlanfulIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 439
Fair value at the ending		$ 440		$ 439
Investment, Identifier [Axis]: Planful, Inc., Equity Securities, Class A Units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PlanfulInc.Member		mrcc:PlanfulInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 563
Fair value at the ending		$ 805		$ 563
Number of units held		473,082		473,082
Investment, Identifier [Axis]: Planful, Inc., Equity Securities, Class B Units
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held		35,791
Investment, Identifier [Axis]: Polychem Acquisition, L L C, Senior Secured Loans, due 3/17/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Prototek LLC (Delayed Draw), Senior Secured Loans, Due 12/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PrototekLlcMember		mrcc:PrototekLlcMember
Investment, Identifier [Axis]: Prototek LLC (Revolver), Senior Secured Loans, Due 12/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PrototekLlcMember		mrcc:PrototekLlcMember
Investment, Identifier [Axis]: Prototek LLC, Senior Secured Loans, Due 12/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:PrototekLlcMember		mrcc:PrototekLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,425
Fair value at the ending		2,463		$ 2,425
Investment, Identifier [Axis]: Quest Resource Management Group, L L C ( Delayed Draw), Senior Secured Loans, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 381
Fair value at the ending				$ 381
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securites, Two, Warrants
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:QuestResourceManagementGroupLLCMember		mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 147
Fair value at the ending		$ 148		$ 147
Warrants to purchase percentage of equity		0.20%		0.20%
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Equity Securities, One, Warrants
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:QuestResourceManagementGroupLLCMember		mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 210
Fair value at the ending		$ 211		$ 210
Warrants to purchase percentage of equity		0.20%		0.20%
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, One, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:QuestResourceManagementGroupLLCMember		mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 972
Fair value at the ending		$ 877		$ 972
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Three, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:QuestResourceManagementGroupLLCMember		mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,781
Fair value at the ending		$ 3,410		$ 3,781
Investment, Identifier [Axis]: Quest Resource Management Group, L L C, Senior Secured Loans, Two, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:QuestResourceManagementGroupLLCMember		mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,067
Fair value at the ending		$ 963		$ 1,067
Investment, Identifier [Axis]: Quest Resource Management Group, LLC, Senior Secured Loans, Four, Due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:QuestResourceManagementGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 344
Investment, Identifier [Axis]: Radiology Partners, Inc., Senior Secured Loans, due 7/9/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RadiologyPartnersIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 3,610
Investment, Identifier [Axis]: Recorded Future, Inc, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Recorded Future, Inc [ Member]		Recorded Future, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 225
Fair value at the ending		$ 269		$ 225
Number of units held		80,486		80,486
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C ( Revolver), Senior Secured Loans, due 8/4/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RecycledPlasticsIndustriesLLCMember		mrcc:RecycledPlasticsIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 179
Investment, Identifier [Axis]: Recycled Plastics Industries, L L C, Senior Secured Loans, due 8/4/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RecycledPlasticsIndustriesLLCMember		mrcc:RecycledPlasticsIndustriesLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,370
Fair value at the ending		$ 3,134		$ 3,370
Investment, Identifier [Axis]: Relativity O D A L L C ( Revolver), Senior Secured Loans, due 5/12/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RelativityODALLCMember		mrcc:RelativityODALLCMember
Investment, Identifier [Axis]: Relativity O D A L L C, Senior Secured Loans, due 5/12/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RelativityODALLCMember		mrcc:RelativityODALLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,060
Fair value at the ending		2,107		$ 2,060
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Delayed Draw), Senior Secured Loans, due, 11/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 648
Fair value at the ending				$ 648
Investment, Identifier [Axis]: Relevate Health Group, L L C ( Revolver), Senior Secured Loans, due, 11/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RelevateHealthGroupLLCMember		mrcc:RelevateHealthGroupLLCMember
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, Class B common units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RelevateHealthGroupLLCMember		mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Number of units held		40		40
Investment, Identifier [Axis]: Relevate Health Group, L L C, Equity Securities, preferred units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RelevateHealthGroupLLCMember		mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 36
Fair value at the ending		$ 36		$ 36
Number of units held		40		40
Investment, Identifier [Axis]: Relevate Health Group, L L C, Senior Secured Loans, due, 11/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RelevateHealthGroupLLCMember		mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,449
Fair value at the ending		$ 648		$ 1,449
Investment, Identifier [Axis]: Relevate Health Group, LLC, Senior Secured Loans, Two, Due 11/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RelevateHealthGroupLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,449
Investment, Identifier [Axis]: Research Now Group, Inc. and Survey Sampling International, L L C, Senior Secured Loans, due 12/20/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ResearchNowGroupInc.andSurveySamplingInternationalLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,742
Investment, Identifier [Axis]: Rockdale Blackhawk, L L C, Senior Secured Loans, no stated maturity
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:RockdaleBlackhawkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 557
Fair value at the ending				$ 557
Investment, Identifier [Axis]: Rockdale Blackhawk, LLC, Senior Secured Loans, due, 11/30/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:RockdaleBlackhawkLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 557
Investment, Identifier [Axis]: Runner Buyer I N C., Senior Secured Loans, due 10/23/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: S F R Holdco, L L C Equity Securities
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		S F R Holdco, L L C [ Member]	S F R Holdco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning			$ 3,900	3,900
Fair value at the ending			3,900
Percentage of equity interest		24.40%
Percentage of units held		24.40%
Investment, Identifier [Axis]: S F R Holdco, L L C, Junior Secured Loans Due 7/28/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		S F R Holdco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,850	5,850	5,850
Fair value at the ending		$ 5,850	$ 5,850	$ 5,850
Investment, Identifier [Axis]: S I R V A Worldwide Inc., Senior Secured Loans, due 8/4/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SIRVAWorldwideIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,599
Investment, Identifier [Axis]: S T A T S Intermediate Holdings, L L C, Senior Secured Loans, due 7/10/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:STATSIntermediateHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,221
Investment, Identifier [Axis]: S W Ingredients Holdings, L L C, Senior Secured Loans, due 7/3/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: SFR Holdco, LLC, Equity Securities, 24.4% of Interest
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		S F R Holdco, L L C [ Member]		mrcc:SfrHoldcoLlcEquitySecurities24.4OfInterestMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,900
Fair value at the ending		$ 3,900		$ 3,900
Percentage of equity interest				24.40%
Percentage of units held			24.40%
Investment, Identifier [Axis]: Sandvine Corporation, Senior Secured Loans, due 10/31/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SandvineCorporationMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,869
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C ( Revolver), Senior Secured Loans, Due 8/9/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		Second Avenue S F R Holdings I I L L C [ Member]		Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,755	$ 2,104	$ 2,104
Purchases (cost)			488
Net unrealized gain (loss)		6
Fair value at the ending		4,761	$ 2,592	$ 4,755
Investment, Identifier [Axis]: Second Avenue S F R Holdings I I L L C, Junior Secured Loans, Due 7/28/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 5,850
Fair value at the ending				$ 5,850
Investment, Identifier [Axis]: Secretariat Advisors L L C, Senior Secured Loans, due 12/29/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecretariatAdvisorsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,642
Investment, Identifier [Axis]: Secretariat Advisors LLC, Senior Secured Loans, Two, due 12/29/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecretariatAdvisorsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 262
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Five, due 9/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecurityServicesAcquisitionSubCorpMember		mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,532
Fair value at the ending		$ 1,527		$ 1,532
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Four, due 9/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecurityServicesAcquisitionSubCorpMember		mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,131
Fair value at the ending		$ 2,124		$ 2,131
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, One, due 9/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecurityServicesAcquisitionSubCorpMember		mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,372
Fair value at the ending		$ 3,361		$ 3,372
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Three, due 9/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecurityServicesAcquisitionSubCorpMember		mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 7,884
Fair value at the ending		$ 7,860		$ 7,884
Investment, Identifier [Axis]: Security Services Acquisition Sub Corp., Senior Secured Loans, Two, due 9/30/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SecurityServicesAcquisitionSubCorpMember		mrcc:SecurityServicesAcquisitionSubCorpMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,425
Fair value at the ending		$ 2,418		$ 2,425
Investment, Identifier [Axis]: Seran Bio Science, L L C ( Revolver), Senior Secured Loans, due 7/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember		mrcc:SeranBioScienceLLCMember
Investment, Identifier [Axis]: Seran Bio Science, L L C, Equity Securities, common units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember		mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 537
Fair value at the ending		$ 733		$ 537
Number of units held		33,333		33,333
Investment, Identifier [Axis]: Seran Bio Science, L L C, Senior Secured Loans, due 7/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember		mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,435
Fair value at the ending		$ 2,425		$ 2,435
Investment, Identifier [Axis]: Seran BioScience, LLC (Delayed Draw), Senior Secured Loans, Due 7/8/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SeranBioScienceLLCMember		mrcc:SeranBioScienceLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,320
Fair value at the ending		1,975		$ 1,320
Investment, Identifier [Axis]: Service Max, Inc. ( Revolver) , Senior Secured Loans, due 11/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ServiceMaxIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		175
Fair value at the ending				$ 175
Investment, Identifier [Axis]: Service Max, Inc., Senior Secured Loans, due 11/1/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ServiceMaxIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,884
Fair value at the ending				$ 3,884
Investment, Identifier [Axis]: Sparq Holdings Inc. Delayed Draw Senior Secured Loans Due 6/15/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SparqHoldingsInc.Member
Investment, Identifier [Axis]: Sparq Holdings Inc. Revolver Senior Secured Loans Due 6/15/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SparqHoldingsInc.Member
Investment, Identifier [Axis]: Sparq Holdings Inc. Senior Secured Loans Due 6/15/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SparqHoldingsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 970
Investment, Identifier [Axis]: Sparq Holdings, Inc. Senior Secured Loans
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SparqHoldingsInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 300
Number of shares held		300,000
Investment, Identifier [Axis]: Spectrum Science Communications, L L C ( Revolver), Senior Secured Loans, due 1/25/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:SpectrumScienceCommunicationsLLCMember
Investment, Identifier [Axis]: Spectrum Science Communications, L L C, Senior Secured Loans, due 1/25/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:SpectrumScienceCommunicationsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,005
Fair value at the ending				$ 1,005
Investment, Identifier [Axis]: Spherix Global Inc, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SpherixGlobalIncMember		mrcc:SpherixGlobalInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 63
Fair value at the ending		$ 54		$ 63
Number of units held		81		81
Investment, Identifier [Axis]: Spherix Global Inc. ( Revolver), Senior Secured Loans, due, 12/22/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SpherixGlobalInc.Member		mrcc:SpherixGlobalIncMember
Investment, Identifier [Axis]: Spherix Global Inc. , Senior Secured Loans, due, 12/22/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SpherixGlobalInc.Member		mrcc:SpherixGlobalIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,088
Fair value at the ending		$ 1,052		$ 1,088
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Delayed Draw), Due 11/3/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SportsOperatingHoldingsIiLlcMember		mrcc:SportsOperatingHoldingsIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 244
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC (Revolver), Due, 11/3/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SportsOperatingHoldingsIiLlcMember		mrcc:SportsOperatingHoldingsIiLlcMember
Investment, Identifier [Axis]: Sports Operating Holdings II, LLC, Due, 11/3/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:SportsOperatingHoldingsIiLlcMember		mrcc:SportsOperatingHoldingsIiLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,918
Fair value at the ending		$ 2,992		$ 2,918
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, ( Revolver), Senior Secured Loans, due 1/12/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StarComplianceMidCoLLCMember		mrcc:StarComplianceMidCoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 79
Fair value at the ending		$ 92		$ 79
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, One, due 1/12/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StarComplianceMidCoLLCMember		mrcc:StarComplianceMidCoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,968
Fair value at the ending		$ 1,978		$ 1,968
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, Three, due 1/12/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StarComplianceMidCoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 254
Investment, Identifier [Axis]: Star Compliance Mid Co, L L C, Senior Secured Loans, Two, due 1/12/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:StarComplianceMidCoLLCMember		mrcc:StarComplianceMidCoLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 330
Fair value at the ending		$ 332		$ 330
Investment, Identifier [Axis]: T A T T Buyer, L L C, Senior Secured Loans, due 3/30/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TATTBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 3,300
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, One, due 4/17/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TCFIIIOWLBuyerLLCMember		mrcc:TCFIIIOWLBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,022
Fair value at the ending		$ 2,009		$ 2,022
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Three, due 4/17/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TCFIIIOWLBuyerLLCMember		mrcc:TCFIIIOWLBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,215
Fair value at the ending		$ 2,202		$ 2,215
Investment, Identifier [Axis]: T C F I I I O W L Buyer L L C, Senior Secured Loans, Two, due 4/17/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TCFIIIOWLBuyerLLCMember		mrcc:TCFIIIOWLBuyerLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,469
Fair value at the ending		$ 2,453		$ 2,469
Investment, Identifier [Axis]: T E A M Public Choices, L L C, Senior Secured Loans, due 12/17/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: T G G T S Acquisition Company, Senior Secured Loans, due 12/12/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TGGTSAcquisitionCompanyMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 3,118
Investment, Identifier [Axis]: T J C Spartech Acquisition Corp., Senior Secured Loans, due 5/5/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: T J Management Hold Co L L C ( Revolver), Senior Secured Loans, Due 6/28/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments		Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		T J Management Hold Co L L C [ Member]		T J Management Hold Co L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 80
Fair value at the ending		$ 80		$ 80
Investment, Identifier [Axis]: T J Management Hold Co L L C, Equity Securities, Common stock
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled affiliate company investments	Non-controlled affiliate company investments	Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]	T J Management Hold Co L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,766	$ 3,148	$ 3,148
Net unrealized gain (loss)		132	(118)
Fair value at the ending		$ 2,898	$ 3,030	$ 2,766
Number of shares held		16	16
Investment, Identifier [Axis]: TJ Management HoldCo LLC, Equity Securities, due 9/9/2020
Transactions with Affiliated Companies, Fair value Roll Forward
Number of shares held				16
Investment, Identifier [Axis]: Tait L L C ( Revolver), Senior Secured Loans, due 3/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TaitLLCMember
Investment, Identifier [Axis]: Tait L L C, Senior Secured Loans, due 3/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TaitLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,013
Investment, Identifier [Axis]: Teneo Holdings L L C, Senior Secured Loans, due 7/11/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TeneoHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,819
Investment, Identifier [Axis]: The Cook & Boardman Group L L C, Senior Secured Loans, due 10/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: The Kleinfelder Group, Inc., Senior Secured Loans, due 11/29/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: The Kyjen Company, L L C ( Revolver), Senior Secured Loans, due 4/3/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TheKyjenCompanyLLCMember		mrcc:TheKyjenCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 88
Fair value at the ending				$ 88
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior SEcured Loans, Two, Due 4/3/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TheKyjenCompanyLLCMember		mrcc:TheKyjenCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1
Investment, Identifier [Axis]: The Kyjen Company, L L C, Senior Secured Loans, due 4/3/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TheKyjenCompanyLLCMember		mrcc:TheKyjenCompanyLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 975
Fair value at the ending		$ 976		$ 975
Investment, Identifier [Axis]: Thrasio, L L C, Senior Secured Loans, due 12/18/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ThrasioLLCMember		mrcc:ThrasioLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,445
Fair value at the ending		$ 2,414		$ 2,445
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Delayed Draw), Senior Secured Loans, due 2/16/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TigerConnectIncMember		mrcc:TigerConnectIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 27
Fair value at the ending		$ 81		$ 27
Investment, Identifier [Axis]: Tiger Connect, Inc. ( Revolver), Senior Secured Loans, due 2/16/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TigerConnectIncMember		mrcc:TigerConnectIncMember
Investment, Identifier [Axis]: Tiger Connect, Inc., Senior Secured Loans, due 2/16/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:TigerConnectIncMember		mrcc:TigerConnectIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,963
Fair value at the ending		$ 2,936		$ 2,963
Investment, Identifier [Axis]: Trident Maritime Systems, Inc ( Revolver), Senior Secured Loans, due 2/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, One, due 2/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Trident Maritime Systems, Inc, Senior Secured Loans, Two, due 2/26/2027
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, One, due 12/14/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Truck- Lite Co., L L C, Senior Secured Loans, Two, due 12/14/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Truck-Lite Co., LLC, Senior Secured Loans, Three, due 12/14/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: V B E1, L L C ( Delayed Draw), Unitranche Secured Loans, due 11/18/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VBE1LLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,264
Investment, Identifier [Axis]: V B E1, L L C, Unitranche Secured Loans, due 11/18/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:VBE1LLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,257
Fair value at the ending				$ 2,257
Investment, Identifier [Axis]: V P S Holdings, L L C ( Revolver), Senior Secured Loans, due 10/4/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VPSHoldingsLLCMember		mrcc:VPSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 102
Fair value at the ending		$ 703		$ 102
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, One, due 10/4/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VPSHoldingsLLCMember		mrcc:VPSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,252
Fair value at the ending		$ 2,661		$ 3,252
Investment, Identifier [Axis]: V P S Holdings, L L C, Senior Secured Loans, Two, due 10/4/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VPSHoldingsLLCMember		mrcc:VPSHoldingsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,661
Fair value at the ending		$ 2,184		$ 2,661
Investment, Identifier [Axis]: V10 Entertainment, Inc, Equity Securities, Common Units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:V10EntertainmentInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 194
Number of shares held		392,157
Investment, Identifier [Axis]: V10 Entertainment, Inc. (Revolver), Senior Secured Loans, Due 1/12/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:V10EntertainmentInc.Member
Investment, Identifier [Axis]: V10 Entertainment, Inc., Senior Secured Loans, Due 1/12/2028
Transactions with Affiliated Companies
Investment, Issuer Name [Extensible Enumeration]		mrcc:V10EntertainmentInc.Member
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 4,016
Investment, Identifier [Axis]: Valudor Products L L C ( Revolver), Senior Secured Loans, due 6/19/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 55
Fair value at the ending				$ 55
Investment, Identifier [Axis]: Valudor Products L L C , Equity Securities, Class A-1 units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ValudorProductsLLCMember		mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 555
Fair value at the ending		$ 521		$ 555
Number of units held		501,014		501,014
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, One, due 6/19/2023,
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,958
Fair value at the ending				$ 1,958
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Three, due 6/19/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,565
Fair value at the ending				$ 1,565
Investment, Identifier [Axis]: Valudor Products L L C, Senior Secured Loans, Two, due 6/19/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 312
Fair value at the ending				$ 312
Investment, Identifier [Axis]: Valudor Products LLC (Revolver), Senior Secured Loans, due 9/15/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ValudorProductsLLCMember
Investment, Identifier [Axis]: Valudor Products LLC, Senior Secured Loans, One, due 9/15/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,924
Investment, Identifier [Axis]: Valudor Products LLC, Senior Secured Loans, Three, due 9/15/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,478
Investment, Identifier [Axis]: Valudor Products LLC, Senior Secured Loans, Two, due 9/15/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ValudorProductsLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 271
Investment, Identifier [Axis]: Vhagar Purchaser, LLC (Delayed Draw), Senior Secured Loans, due 6/8/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VhagarPurchaserLlcMember
Investment, Identifier [Axis]: Vhagar Purchaser, LLC (Revolver), Senior Secured Loans, due, 6/8/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VhagarPurchaserLlcMember
Investment, Identifier [Axis]: Vhagar Purchaser, LLC, Senior Secured Loans, due 6/8/2029
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:VhagarPurchaserLlcMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 2,910
Investment, Identifier [Axis]: Vice Group Holding Inc., Junior Secured Loans, Five, No Maturity Date
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 342
Investment, Identifier [Axis]: Vice Group Holding Inc., Junior Secured Loans, Four, No Maturity Date
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 136
Investment, Identifier [Axis]: Vice Group Holding Inc., Junior Secured Loans, One, No Maturity Date
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,139
Investment, Identifier [Axis]: Vice Group Holding Inc., Junior Secured Loans, Three, No Maturity Date
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 358
Investment, Identifier [Axis]: Vice Group Holding Inc., Junior Secured Loans, Two, No Maturity Date
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 219
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Four, due 5/12/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 196
Fair value at the ending				$ 196
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 11/17/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 88
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, One, due 5/12/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		1,657
Fair value at the ending				$ 1,657
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Three, due 5/12/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 520
Fair value at the ending				$ 520
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 11/17/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 400
Investment, Identifier [Axis]: Vice Group Holding Inc., Senior Secured Loans, Two, due 5/12/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:ViceGroupHoldingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 318
Fair value at the ending				$ 318
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Four, due 2/6/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, One, due 2/6/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Three, due 2/6/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: Vinci Brands L L C, Unitranche Secured Loans, Two, due 2/6/2024
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:VinciBrandsLLCMember
Investment, Identifier [Axis]: W3 Monroe R E Debt L L C, Senior Secured Loans, due 2/4/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:W3MonroeREDebtLLCMember		mrcc:W3MonroeREDebtLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 3,210
Fair value at the ending		$ 3,354		$ 3,210
Investment, Identifier [Axis]: W3 Monroe RE Debt LLC (Delayed Draw), Senior Secured Loans, Due 2/4/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:W3MonroeREDebtLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 21
Investment, Identifier [Axis]: Wheel Pros, Inc., Senior Secured Loans, due 5/11/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Delayed Draw), Senior Secured Loans, due 6/2/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WhistlerParentHoldingsIIIIncMember		mrcc:WhistlerParentHoldingsIIIIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 56
Fair value at the ending		$ 55		$ 56
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc. ( Revolver), Senior Secured Loans, due 6/2/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WhistlerParentHoldingsIIIIncMember		mrcc:WhistlerParentHoldingsIIIIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 84
Fair value at the ending		$ 555		$ 84
Investment, Identifier [Axis]: Whistler Parent Holdings I I I, Inc., Senior Secured Loans, due 6/2/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WhistlerParentHoldingsIIIIncMember		mrcc:WhistlerParentHoldingsIIIIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,457
Fair value at the ending		4,437		$ 4,457
Investment, Identifier [Axis]: WillowTree, LLC, Unitranche Secured Loans, due 10/9/2023
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:WillowTreeLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 7,326
Fair value at the ending				$ 7,326
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C ( Delayed Draw), Junior Secured Loans, due 7/2/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WitkoffMonroe700JVLLCMember		mrcc:WitkoffMonroe700JVLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 6,014
Fair value at the ending		$ 308		$ 6,014
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C, Equity Securities, Preferred units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WitkoffMonroe700JVLLCMember		mrcc:WitkoffMonroe700JVLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,047
Fair value at the ending		$ 1,664		$ 1,047
Number of units held		2,141		2,141
Investment, Identifier [Axis]: Witkoff/ Monroe 700 J V L L C, Junior Secured Loans, due 7/2/2026
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:WitkoffMonroe700JVLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 6,755
Investment, Identifier [Axis]: Xan Edu Publishing, Inc, Equity Securities, Class A units
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember		mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 223
Fair value at the ending		$ 215		$ 223
Number of units held		49,479		49,479
Investment, Identifier [Axis]: Xan Edu Publishing, Inc. ( Revolver), Senior Secured Loans, due, 1/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember		mrcc:XanEduPublishingIncMember
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, One, due, 1/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember		mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,829
Fair value at the ending		$ 4,561		$ 1,829
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, Two, due, 1/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the ending		$ 1,815
Investment, Identifier [Axis]: Xan Edu Publishing, Inc., Senior Secured Loans, due, 1/28/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]				Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]				mrcc:XanEduPublishingIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 4,602
Fair value at the ending				$ 4,602
Investment, Identifier [Axis]: Y S W H 4, L L C (Revolver), Senior Secured Loans, Due 11/20/2025
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:YSWH4LLCRevolverMember		mrcc:YSWH4LLCRevolverMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 1,776
Fair value at the ending				$ 1,776
Investment, Identifier [Axis]: iCIMS, Inc., Senior Secured Loans, Due 8/18/2028
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]		Non-controlled/non-affiliate company investments		Non-controlled/non-affiliate company investments
Investment, Issuer Name [Extensible Enumeration]		mrcc:IcimsIncMember		mrcc:IcimsIncMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		$ 2,456
Fair value at the ending		2,500		$ 2,456
Non-controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		86,618	$ 90,281	90,281
Purchases (cost)		1,939	763
Sales and paydowns (cost)		(6,175)	(654)
PIK Interest (cost)		3,172	1,917
Discount accretion		26	23
Net unrealized gain (loss)		(1,534)	(1,299)
Fair value at the ending		84,046	$ 91,031	86,618
Non-controlled affiliate company investments | American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			American Community Homes, Inc. [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		19,546	$ 23,748	23,748
PIK Interest (cost)		1,779	1,120
Net unrealized gain (loss)		(2,061)	(2,883)
Fair value at the ending		19,264	$ 21,985	19,546
Non-controlled affiliate company investments | Ascent Midco, L L C [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			Ascent Midco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		8,186	$ 8,946	8,946
Sales and paydowns (cost)		(6,175)	(87)
Discount accretion		16	14
Net unrealized gain (loss)		(101)	(951)
Fair value at the ending		1,926	$ 7,922	8,186
Non-controlled affiliate company investments | C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			C Parent Holdings, LLC. (fka Curion Holdings, LLC) [Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		146	$ 5,111	5,111
Purchases (cost)			92
Sales and paydowns (cost)			(567)
Net unrealized gain (loss)		(146)	1,607
Fair value at the ending			$ 6,243	146
Non-controlled affiliate company investments | Familia Dental Group Holdings, LLC
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			Familia Dental Group Holdings, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		2,625	$ 1,919	1,919
Purchases (cost)		60	183
Net unrealized gain (loss)		(244)	653
Fair value at the ending		2,441	$ 2,755	2,625
Non-controlled affiliate company investments | H F Z Capital Group, L L C And M C Asset Management ( Corporate), L L C [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			mrcc:MCAssetManagementCorporateLLCMember
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		32,676	$ 29,152	29,152
Purchases (cost)		1,586
PIK Interest (cost)		1,015	660
Net unrealized gain (loss)		846	519
Fair value at the ending		36,123	$ 30,331	32,676
Non-controlled affiliate company investments | Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			Mnine Holdings, Inc [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		5,706	$ 5,771	5,771
Purchases (cost)		293
PIK Interest (cost)		378	137
Discount accretion		10	9
Net unrealized gain (loss)		(10)	(9)
Fair value at the ending		6,377	$ 5,908	5,706
Non-controlled affiliate company investments | N E C B Collections, L L C [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			N E C B Collections, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		382	$ 632	632
Net unrealized gain (loss)		44	(117)
Fair value at the ending		426	$ 515	382
Non-controlled affiliate company investments | Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			Second Avenue S F R Holdings I I L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		4,755	$ 2,104	2,104
Purchases (cost)			488
Net unrealized gain (loss)		6
Fair value at the ending		4,761	$ 2,592	4,755
Non-controlled affiliate company investments | S F R Holdco, L L C [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			S F R Holdco, L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		9,750	$ 9,750	9,750
Fair value at the ending		9,750	$ 9,750	9,750
Non-controlled affiliate company investments | T J Management Hold Co L L C [ Member]
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Non-controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			T J Management Hold Co L L C [ Member]
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		2,846	$ 3,148	3,148
Net unrealized gain (loss)		132	(118)
Fair value at the ending		2,978	3,030	2,846
Controlled affiliate company investments
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		35,509	41,125	41,125
Purchases (cost)			500
Net unrealized gain (loss)		(964)	(4,074)
Fair value at the ending		34,545	$ 37,551	35,509
Controlled affiliate company investments | MRCC Senior Loan Fund I, LLC
Transactions with Affiliated Companies
Investment, Issuer Affiliation [Extensible Enumeration]			Controlled affiliate company investments
Investment, Issuer Name [Extensible Enumeration]			MRCC Senior Loan Fund I, LLC
Transactions with Affiliated Companies, Fair value Roll Forward
Fair value at the beginning		35,509	$ 41,125	41,125
Purchases (cost)			500
Net unrealized gain (loss)		(964)	(4,074)
Fair value at the ending		$ 34,545	$ 37,551	$ 35,509