Related Party Transactions - Fees And Expenses Accrued Under The Investment Advisory Agreement (Details) - USD ($) $ in Millions		12 Months Ended			42 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2024
Related Party Transaction [Line Items]
Base Management Fee		$ 216.0	$ 226.0	$ 245.0
Subordinated Incentive Fee on Income	[1]	167.0	181.0	159.0
Administrative Services Expenses		4.0	4.0	5.0
Management and investment adviser fees payable		53.0	56.0		$ 53.0
Subordinated income incentive fees payable	[2]	35.0	41.0		35.0
FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Base Management Fee		216.0	226.0	245.0
Subordinated Incentive Fee on Income		167.0	181.0	99.0
Administrative Services Expenses		10.0	12.0	15.0
Base management fees		219.0	229.0	246.0
Management and investment adviser fees payable		53.0			53.0
Incentive fees waived quarterly					15.0
Incentive fee waiver				60.0
Incentive fee paid		173.0	167.0	91.0
Subordinated income incentive fees payable		35.0			$ 35.0
Allocation of costs of administrative personnel for services rendered		9.0	11.0	13.0
Broken deal cost		0.9
Payment for administrative services expenses		$ 12.0	$ 13.0	$ 14.0

[1] See Note 2 and 4 for a discussion of the methodology employed by the Company in calculating the subordinated income incentive fees.

[2] See Note 2 and 4 for a discussion of the methodology employed by the Company in calculating the subordinated income incentive fees.