Quarterly report pursuant to Section 13 or 15(d)

RELATED PARTY TRANSACTIONS (Details)

v3.24.3
RELATED PARTY TRANSACTIONS (Details) - Related Party - USD ($)
 1 Months Ended 9 Months Ended
Sep. 30, 2023
Aug. 31, 2023
Mar. 31, 2022
Feb. 28, 2022
Dec. 31, 2020
Sep. 30, 2024
Aug. 31, 2024
May 31, 2024
Jan. 31, 2024
Oct. 31, 2023
May 31, 2023
External Investment Manager                      
Related Party Transaction [Line Items]                      
Receivable           $ 9,000,000.0          
MSC Income                      
Related Party Transaction [Line Items]                      
Shares acquired (in shares)   348,542       2,170,223 250,627 315,259 314,070 475,888 255,755
Operating Expenses and Amount Due From Tax Sharing Agreement | External Investment Manager                      
Related Party Transaction [Line Items]                      
Receivable           $ 6,400,000          
Dividends Declared But Not Yet Paid | External Investment Manager                      
Related Party Transaction [Line Items]                      
Receivable           2,600,000          
Dutch Auction | MSC Income                      
Related Party Transaction [Line Items]                      
Shares acquired (in shares) 115,385                    
Sale of stock, price per share (in dollars per share) $ 6.50                    
Sale of stock, authorized consideration on transaction   $ 3,500,000                  
Investment Management Agreement | Private Loan Fund                      
Related Party Transaction [Line Items]                      
Amounts of transaction       $ 15,000,000.0 $ 10,000,000.0            
Funded commitments           14,200,000          
Unfunded commitments           800,000          
Investment Management Agreement | Private Loan Fund II                      
Related Party Transaction [Line Items]                      
Amounts of transaction $ 15,000,000.0                    
Funded commitments           7,400,000          
Unfunded commitments           5,000,000.0          
Percentage of total commitments (as a percent) 20.00%                    
Secured Revolving Promissory Note | Private Loan Fund                      
Related Party Transaction [Line Items]                      
Amounts of transaction     $ 10,000,000.0                
Interest rate (as a percent)     5.00%                
Unused capacity, commitment fee (as a percent)     0.25%                
Amount of debt outstanding           0          
Secured Revolving Promissory Note | Private Loan Fund II                      
Related Party Transaction [Line Items]                      
Amounts of transaction $ 50,000,000.0                    
Interest rate (as a percent) 3.50%                    
Unused capacity, commitment fee (as a percent) 0.25%                    
Amount of debt outstanding           33,500,000          
Interest rate, floor (as a percent) 2.00%                    
2015 Deferred Compensation Plan                      
Related Party Transaction [Line Items]                      
Amounts of transaction           24,700,000          
2015 Deferred Compensation Plan | Rabbi Trust                      
Related Party Transaction [Line Items]                      
Amounts of transaction           $ 15,500,000          
2015 Deferred Compensation Plan | Common Stock                      
Related Party Transaction [Line Items]                      
Deferred compensation (in shares)           183,990          
2015 Deferred Compensation Plan | Phantom Stock Units                      
Related Party Transaction [Line Items]                      
Amounts of transaction           $ 9,200,000          
2015 Deferred Compensation Plan | Private Loan Fund | Rabbi Trust                      
Related Party Transaction [Line Items]                      
Amounts of transaction           2,100,000          
2015 Deferred Compensation Plan | Private Loan Fund II | Rabbi Trust                      
Related Party Transaction [Line Items]                      
Amounts of transaction           $ 3,100,000