Investment Portfolio - Operations Information for COPJV (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Expenses
Interest expense	[1]	$ 116.0	$ 114.0
Professional services		3.0	3.0
Credit Opportunities Partners JV, LLC
Investment Company, Nonconsolidated Subsidiary [Line Items]
Total investment income		90.6	93.1
Expenses
Interest expense		32.4	29.4
Custodian and accounting fees		0.4	0.4
Administrative services		2.4	2.4
Professional services		0.1	0.1
Other		0.2	0.2
Total expenses		35.5	32.5
Net investment income		55.1	60.6
Net realized and unrealized gain (loss)		(2.6)	(33.8)
Net increase in net assets resulting from operations		$ 52.5	$ 26.8

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