Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Structuring Fees
Related Party Transaction [Line Items]
Structuring fee revenue	$ 29	$ 34
Investment Advisory Agreement - Incentive Rate, Realized Capital Gains | FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Incentive fee (in percent)	20.00%
Investment Advisory Agreement - Incentive Rate, Quarterly Catch-up Threshold | FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Incentive fee (in percent)	1.75%
Investment Advisory Agreement - Incentive Rate, Quarterly In Arrears Catch-up Threshold | FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Incentive fee (in percent)	17.50%
Investment Advisory Agreement - Incentive Rate, Annualized Hurdle Rate | FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Incentive fee (in percent)	7.00%
Investment Advisory Agreement - Incentive Rate, Pre-Incentive Fee Net Investment Income Below Catch-Up Threshold | FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Incentive fee (in percent)	2.12%
Investment Advisory Agreement - Incentive Rate, Annualized Catch-Up Threshold | FS/KKR Advisor, LLC
Related Party Transaction [Line Items]
Incentive fee (in percent)	8.48%