Quarterly report [Sections 13 or 15(d)]

RELATED PARTY TRANSACTIONS - Summarizes of Main Street???s Purchases (Details)

v3.25.1
RELATED PARTY TRANSACTIONS - Summarizes of Main Street’s Purchases (Details)
$ / shares in Units, $ in Thousands
Dec. 16, 2024
Aug. 16, 2023
USD ($)
Mar. 31, 2025
USD ($)
shares
Jan. 30, 2025
USD ($)
$ / shares
shares
Dec. 31, 2024
USD ($)
 [4],[5]
Aug. 01, 2024
USD ($)
$ / shares
shares
May 01, 2024
USD ($)
$ / shares
shares
Jan. 31, 2024
USD ($)
$ / shares
shares
Oct. 31, 2023
USD ($)
$ / shares
shares
Sep. 25, 2023
USD ($)
$ / shares
shares
Aug. 01, 2023
USD ($)
$ / shares
shares
May 01, 2023
USD ($)
$ / shares
shares
May 02, 2022
USD ($)
$ / shares
shares
Related Party Transaction [Line Items]                          
Total Cost (in thousands)     $ 4,295,736 [1],[2],[3]   $ 4,237,312                
MSC Income                          
Related Party Transaction [Line Items]                          
Reverse stock split 0.5                        
MSC Income | Related Party                          
Related Party Transaction [Line Items]                          
Shares Purchased (in shares) | shares     1,374,872 289,761   125,314 157,629 157,035 237,944   174,271 127,877 47,349
Price per share (in dollars per share) | $ / shares       $ 15.53   $ 15.96 $ 15.86 $ 15.92 $ 15.76   $ 15.78 $ 15.64 $ 15.84
Total Cost (in thousands)       $ 4,500   $ 2,000 $ 2,500 $ 2,500 $ 3,750   $ 2,750 $ 2,000 $ 750
MSC Income | Related Party | Dutch Auction                          
Related Party Transaction [Line Items]                          
Shares Purchased (in shares) | shares                   57,692      
Price per share (in dollars per share) | $ / shares                   $ 13.00      
Total Cost (in thousands)                   $ 750      
Sale of stock, authorized consideration on transaction   $ 3,500                      
[1] All portfolio company headquarters are based in the United States, unless otherwise noted.
[2] All investments are Lower Middle Market portfolio investments, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for a description of Lower Middle Market portfolio investments. All of the Company’s investments, unless otherwise noted, are encumbered either as security for the Company’s Corporate Facility or SPV Facility (each as defined in Note B.5. — Summary of Significant Accounting Policies —Deferred Financing Costs, and together the “Credit Facilities”) or in support of the SBA-guaranteed debentures issued by the Funds.
[3] Principal is net of repayments. Cost is net of repayments and accumulated unearned income. Negative cost is the result of the capitalized discount being greater than the principal amount outstanding on the loan.
[4] All portfolio company headquarters are based in the United States, unless otherwise noted.
[5] All investments are Lower Middle Market portfolio investments, unless otherwise noted. See Note C — Fair Value Hierarchy for Investments — Portfolio Composition for a description of Lower Middle Market portfolio investments. All of the Company’s investments, unless otherwise noted, are encumbered either as security for the Company’s Corporate Facility or SPV Facility (each as defined in Note B.5. — Summary of Significant Accounting Policies —Deferred Financing Costs, and together the “Credit Facilities”) or in support of the SBA-guaranteed debentures issued by the Funds.