Investments - 2025-1 Notes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Dec. 31, 2025
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 2,127,000	$ 2,077,000
Bain Capital Senior Loan Program, LLC
Debt Instrument [Line Items]
Total aggregate principal amount committed	440,000
Bain Capital Senior Loan Program, LLC \| Class A-1 Notes
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 147,000
Spread rate (as a percent)	1.62%
Effective interest rate	5.29%
Bain Capital Senior Loan Program, LLC \| Class A-1 Loans
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 56,000
Spread rate (as a percent)	1.62%
Effective interest rate	5.29%
Bain Capital Senior Loan Program, LLC \| Class A-2 Loans
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 14,000
Spread rate (as a percent)	1.77%
Effective interest rate	5.44%
Bain Capital Senior Loan Program, LLC \| Class B Notes
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 21,000
Spread rate (as a percent)	1.95%
Effective interest rate	5.62%
Bain Capital Senior Loan Program, LLC \| Class C Notes
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 29,750
Spread rate (as a percent)	2.50%
Effective interest rate	6.17%
Bain Capital Senior Loan Program, LLC \| Class D-1 Notes
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 19,250
Spread rate (as a percent)	3.50%
Effective interest rate	7.17%
Bain Capital Senior Loan Program, LLC \| Class D-2 Notes
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 8,750
Spread rate (as a percent)	5.50%
Effective interest rate	9.17%
Bain Capital Senior Loan Program, LLC \| 2025-1 Notes
Debt Instrument [Line Items]
Total aggregate principal amount committed	$ 295,750