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Investment Portfolio - Narrative (Details) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
Investment Portfolio - Narrative (Details) $ in Millions	Feb. 23, 2026 USD ($)	Jun. 30, 2026 USD ($) company	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($) company	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($) company
Schedule of Investments [Line Items]
Amount funded to joint venture				$ 2,520.0
Net realized gain (loss) on investments:				(272.0)	$ (153.0)
Receivable for investments sold and repaid		$ 310.0		310.0		$ 313.0
Credit Opportunities Partners JV, LLC
Schedule of Investments [Line Items]
Cost basis of investments sold	$ 189.0			84.6		1,805.4
Aggregate credit opportunities partners	175.0
Amount funded to joint venture	2,975.0
Proceeds from sale of investments				84.7		1,829.2
Net realized gain (loss) on investments:				0.1		23.8
Receivable for investments sold and repaid		177.3		177.3
Payments to acquire investments				76.0
Additional gain (loss) realized				$ (0.5)
Credit opportunities partners JV, LLC, entitled to a fee percentage				0.25%
Administrative services		3.6	$ 2.8	$ 6.7	5.1
FS KKR Capital Corp.
Schedule of Investments [Line Items]
Joint venture voting control, percentage				50.00%
Amount funded to joint venture	$ 2,450.0			$ 2,016.0
Contributed capital to committed capital ratio	79.00%
SCRS
Schedule of Investments [Line Items]
Joint venture voting control, percentage				50.00%
Amount funded to joint venture	$ 525.0
Contributed capital to committed capital ratio	21.00%
Credit Opportunities Partners JV, LLC
Schedule of Investments [Line Items]
Unfunded commitments		434.0		$ 434.0		245.0
Unfunded Debt Securities
Schedule of Investments [Line Items]
Unfunded commitments		1,110.5		1,110.5		1,447.4
Unfunded Equity/Other Commitments
Schedule of Investments [Line Items]
Unfunded commitments		$ 70.7		$ 70.7		$ 87.5
Controlled/affiliated
Schedule of Investments [Line Items]
Number of investments in portfolio companies \| company		38		38		34
Net realized gain (loss) on investments:		$ 0.0	(68.0)	$ (55.8)	(55.0)	$ (73.7)
Non-controlled/affiliated
Schedule of Investments [Line Items]
Number of investments in portfolio companies \| company		9		9		10
Net realized gain (loss) on investments:		$ (72.0)	$ (1.0)	$ (170.2)	$ 8.0	$ (2.3)