Investment Portfolio - Operations Information for COPJV (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating expenses
Interest expense	[1]	$ 118.0	$ 83.0	$ 232.0	$ 160.0
Professional services		4.0	4.0	7.0	8.0
Credit Opportunities Partners JV, LLC
Investment Company, Nonconsolidated Subsidiary [Line Items]
Total investment income		97.4	75.8	190.5	136.7
Operating expenses
Interest expense		31.8	11.3	61.2	24.9
Custodian and accounting fees		0.4	0.5	0.8	0.9
Administrative services		2.4	2.2	4.8	4.6
Professional services		0.1	0.0	0.2	0.2
Other		0.4	0.0	0.6	0.1
Total expenses		35.1	14.0	67.6	30.7
Net investment income		62.3	61.8	122.9	106.0
Net realized and unrealized gain (loss)		(17.3)	(64.6)	(51.1)	(63.4)
Net increase in net assets resulting from operations		$ 45.0	$ (2.8)	$ 71.8	$ 42.6

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