Related Party Transactions - Fees And Expenses Accrued Under The Investment Advisory Agreement (Details) - USD ($) $ in Millions		12 Months Ended			18 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Related Party Transaction [Line Items]
Base Management Fee		$ 245.0	$ 173.0	$ 106.0
Subordinated Incentive Fee on Income	[1]	159.0	77.0	0.0
Administrative Services Expenses		5.0	3.0	2.0
Management and investment adviser fees payable		59.0	60.0		$ 59.0
Subordinated income incentive fees payable	[2]	27.0	19.0		27.0
FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Base Management Fee		245.0	173.0	106.0
Subordinated Incentive Fee on Income		99.0	47.0	0.0
Administrative Services Expenses		15.0	12.0	7.0
Base management fees		246.0	162.0	111.0
Management and investment adviser fees payable		59.0			59.0
Incentive fees waived quarterly					15.0
Incentive fee waiver		(60.0)	(30.0)
Incentive fee paid		91.0	49.0	0.0
Subordinated income incentive fees payable		27.0			$ 27.0
Allocation of costs of administrative personnel for services rendered		13.0	10.0	6.0
Broken deal cost		1.3
Payment for administrative services expenses		$ 14.0	$ 11.0	$ 8.0

[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.