Investment Portfolio - Schedule of Operations Information for COPJV (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Expenses
Interest expense	[1]	$ 118.0	$ 117.0	$ 349.0	$ 349.0
Professional services		2.0	3.0	7.0	10.0
Credit Opportunities Partners JV, LLC
Investment Company, Nonconsolidated Subsidiary [Line Items]
Total investment income		85.5	99.3	266.3	289.8
Expenses
Interest expense		29.7	30.4	92.0	91.6
Custodian and accounting fees		1.3	0.4	2.1	1.2
Administrative services		2.2	2.3	6.9	7.1
Professional services		0.1	0.2	0.4	0.4
Other		0.4	0.3	1.0	0.9
Total expenses		33.7	33.6	102.4	101.2
Net investment income		51.8	65.7	163.9	188.6
Net realized and unrealized gain (loss)		(3.7)	25.8	(6.9)	(25.3)
Net increase in net assets resulting from operations		$ 48.1	$ 91.5	$ 157.0	$ 163.3

[1] See Note 9 for a discussion of the Company’s financing arrangements.