Annual report [Section 13 and 15(d), not S-K Item 405]

BORROWINGS - Revolving Line of Credit Narrative (Details)

v3.25.1
BORROWINGS - Revolving Line of Credit Narrative (Details) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Feb. 24, 2025
Debt Instrument [Line Items]      
Indebtedness asset coverage on our senior securities 204.40% 219.00%  
Credit Facility | Line of Credit      
Debt Instrument [Line Items]      
Unused fee percentage 1.00% 1.00%  
Credit Facility | Revolving Line of Credit | Line of Credit      
Debt Instrument [Line Items]      
Commitment amount $ 270,000 $ 200,000 $ 270,000
Line of credit facility, accordion feature maximum borrowing capacity $ 300,000    
Debt instrument, variable rate floor 0.35% 0.35%  
Debt instrument, basis spread on variable rate 3.25% 3.25%  
Covenant, required minimum net worth of mandatory redeemable term preferred stock $ 210,000    
Covenant, required minimum net worth of mandatory redeemable term preferred stock, plus percent of all equity and subordinated debt raised 50.00%    
Covenant, required minimum net worth of mandatory redeemable term preferred stock, minus percent of any equity or subordinated debt redeemed or retired 50.00%    
Covenant, required minimum net worth of mandatory redeemable term preferred stock, plus percent of all equity and subordinated debt raised, minus percent of any equity or subordinated debt redeemed or retired $ 412,900    
Indebtedness asset coverage on our senior securities 204.40%    
Senior security, indebtedness, asset coverage amount $ 953,300    
Credit Facility | Revolving Line of Credit | Line of Credit | Minimum      
Debt Instrument [Line Items]      
Indebtedness asset coverage on our senior securities 150.00%    
Credit Facility | Revolving Line of Credit | Line of Credit | Less than or Equal to 50% of Commitment      
Debt Instrument [Line Items]      
Unused fee percentage 0.50%    
Credit Facility | Revolving Line of Credit | Line of Credit | Greater than 50% but Less than or Equal to 65% of Commitment      
Debt Instrument [Line Items]      
Unused fee percentage 0.75%    
Credit Facility | Revolving Line of Credit | Line of Credit | Greater Than 65% Of Commitment      
Debt Instrument [Line Items]      
Unused fee percentage 1.00%    
Credit Facility | Revolving Line of Credit | Line of Credit | Secured Overnight Financing Rate (SOFR), Adjustment      
Debt Instrument [Line Items]      
Debt instrument, basis spread on variable rate 0.10%    
Credit Facility | Revolving Line of Credit | Line of Credit | SOFR, Tranche One      
Debt Instrument [Line Items]      
Debt instrument, basis spread on variable rate 3.15%    
Credit Facility | Revolving Line of Credit | Line of Credit | SOFR, Tranche Two      
Debt Instrument [Line Items]      
Debt instrument, basis spread on variable rate 3.40%    
Credit Facility | Revolving Line of Credit | Line of Credit | SOFR, Thereafter      
Debt Instrument [Line Items]      
Debt instrument, basis spread on variable rate 3.65%