Quarterly report [Sections 13 or 15(d)]

DEBT - Notes??Due and SBIC Debentures (Details)

v3.25.3
DEBT - Notes Due and SBIC Debentures (Details) - USD ($)
1 Months Ended 9 Months Ended
Aug. 31, 2025
Sep. 30, 2024
Jun. 30, 2024
May 31, 2024
Jan. 31, 2024
Oct. 31, 2021
Jan. 31, 2021
Sep. 30, 2025
Sep. 30, 2024
Dec. 31, 2024
Debt Instrument [Line Items]                    
Debt instrument, outstanding balance               $ 2,161,000,000   $ 2,134,000,000
Debt               2,149,768,000   2,122,371,000
July 2026 Notes | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount           $ 200,000,000.0 $ 300,000,000.0 500,000,000   500,000,000
Debt instrument, interest rate, stated (as a percent)             3.00%      
Debt instrument, issuance price (as a percent)           101.741% 99.004%      
Debt instrument, outstanding balance               500,000,000   500,000,000
Debt               499,583,000   499,188,000
June 2027 Notes | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount     $ 300,000,000.0         400,000,000   400,000,000
Debt instrument, interest rate, stated (as a percent)     6.50%              
Debt instrument, issuance price (as a percent)   102.134% 99.793%              
Yield to maturity rate     6.34%              
Debt instrument, outstanding balance               400,000,000   400,000,000
Debt               399,497,000   399,282,000
June 2027 Notes, Additional | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount   $ 100,000,000.0             $ 100,000,000.0  
Yield to maturity rate   5.617%             5.617%  
August 2028 Notes | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount $ 350,000,000.0             350,000,000    
Debt instrument, interest rate, stated (as a percent) 5.40%                  
Debt instrument, issuance price (as a percent) 99.989%                  
Debt instrument, outstanding balance               350,000,000    
Debt               347,848,000   0
March 2029 Notes | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount         $ 350,000,000.0     350,000,000   350,000,000
Debt instrument, interest rate, stated (as a percent)         6.95%          
Debt instrument, issuance price (as a percent)         99.865%          
Debt instrument, outstanding balance               350,000,000   350,000,000
Debt               347,541,000   347,002,000
SBIC debentures                    
Debt Instrument [Line Items]                    
Repayment of December 2025 Notes               0 $ 63,800,000  
SBIC debentures | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount               350,000,000   350,000,000
Debt instrument, outstanding balance               $ 350,000,000   $ 350,000,000
Debt instrument, term (in years)               10 years    
Debt instrument, weighted-average annual interest rate (as a percent)               3.30%   3.30%
Debt instrument, remaining term (in years)               4 years 10 months 24 days    
Debt               $ 344,299,000   $ 343,417,000
SBIC debentures | Unsecured Notes | MSMF                    
Debt Instrument [Line Items]                    
Debt instrument, face amount               175,000,000.0    
Debt               170,800,000    
Debt instrument, unamortized debt issuance costs               4,200,000    
SBIC debentures | Unsecured Notes | MSC III                    
Debt Instrument [Line Items]                    
Debt instrument, face amount               175,000,000.0    
Debt               173,500,000    
Debt instrument, unamortized debt issuance costs               1,500,000    
SBIC debentures | Unsecured Notes | Maximum                    
Debt Instrument [Line Items]                    
Debt instrument, outstanding balance               350,000,000.0    
May 2024 Notes | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, interest rate, stated (as a percent)       5.20%            
Repayment of December 2025 Notes       $ 450,000,000.0            
December 2025 Series A Notes | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount               $ 100,000,000.0    
Debt instrument, interest rate, stated (as a percent)               7.84%    
December 2025 Series B Notes | Unsecured Notes                    
Debt Instrument [Line Items]                    
Debt instrument, face amount               $ 50,000,000.0    
Debt instrument, interest rate, stated (as a percent)               7.53%