Investments - SLP Schedule of Investments (Parenthetical) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Open Forward Foreign Currency Contract [Line Items]
Net assets	$ 1,093,555	$ 1,117,410	$ 1,144,504	$ 1,139,672
Restricted cash	$ 11,695	$ 26,809
Interest Rate Floor One
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.50%
Interest Rate Floor Two
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.50%	1.00%
Interest Rate Floor Three
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%	0.75%
Interest Rate Floor Four
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%	0.50%
Interest Rate Floor Five
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%	0.00%
Interest Rate Floor Six
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%	0.25%
Interest Rate Floor Seven
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%	1.25%
Bain Capital Senior Loan Program, LLC
Open Forward Foreign Currency Contract [Line Items]
Net assets	$ 5,417	$ 8,078
Restricted cash	$ 46,455	$ 122,290
Bain Capital Senior Loan Program, LLC \| Interest Rate Floor One
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%	1.00%
Bain Capital Senior Loan Program, LLC \| Interest Rate Floor Two
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%	0.75%
Bain Capital Senior Loan Program, LLC \| Interest Rate Floor Three
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%	0.50%
Bain Capital Senior Loan Program, LLC \| Interest Rate Floor Four
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%	0.00%
Bain Capital Senior Loan Program, LLC \| Interest Rate Floor Five
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%	1.25%
Bain Capital Senior Loan Program, LLC \| Interest Rate Floor Six
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%	2.00%
Bain Capital Senior Loan Program, LLC \| Interest Rate Floor Seven
Open Forward Foreign Currency Contract [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%	1.50%