Investment Portfolio - Schedule of Operations Information for COPJV (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Expenses
Interest expense	[1]	$ 115.0	$ 118.0	$ 231.0	$ 232.0
Professional services		2.0	4.0	5.0	7.0
Credit Opportunities Partners JV, LLC
Investment Company, Nonconsolidated Subsidiary [Line Items]
Total investment income		90.2	97.4	180.8	190.5
Expenses
Interest expense		29.9	31.8	62.3	61.2
Custodian and accounting fees		0.4	0.4	0.8	0.8
Administrative services		2.3	2.4	4.7	4.8
Professional services		0.2	0.1	0.3	0.2
Other		0.4	0.4	0.6	0.6
Total expenses		33.2	35.1	68.7	67.6
Net investment income		57.0	62.3	112.1	122.9
Net realized and unrealized gain (loss)		(0.6)	(17.3)	(3.2)	(51.1)
Net increase in net assets resulting from operations		$ 56.4	$ 45.0	$ 108.9	$ 71.8

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