Borrowings - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Debt Disclosure [Abstract]
Asset coverage ratio	211.90%		211.90%		184.50%
Interest expense, payable	$ 333.3		$ 333.3		$ 395.8
Unused borrowing capacity fee payable	$ 14.1		$ 14.1		$ 12.9
Weighted average interest rate	7.12%	4.17%	6.71%	3.27%
Average amount outstanding	$ 23,929.5	$ 27,552.4	$ 25,427.9	$ 22,342.7