FINANCIAL HIGHLIGHTS - Financial Highlights (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Investment Company, Financial Highlights [Roll Forward]
Net asset value, beginning of period (in dollars per share)	$ 19.24	$ 18.40
Issuances of common stock (in dollars per share)	0.06	0.01
Conversion of 2024 Convertible Notes (in dollars per share)	0.01	0
Net investment income for period (in dollars per share)	1.70	1.68
Net realized and unrealized gains (losses) for period (in dollars per share)	0.20	0.34
Net increase in stockholders' equity resulting from operations (in dollars per share)	1.97	2.03
Total distributions to stockholders (in dollars per share)	(1.44)	(1.44)
Net asset value, end of period (in dollars per share)	19.77	18.99
Per share market value at end of period (in dollars per share)	$ 20.94	$ 19.47			$ 20.03			$ 18.47
Total return based on market value	12.12%	13.81%
Total return based on net asset value	10.48%	11.37%
Shares outstanding at end of period (in shares)	646	569			582
Ratio/Supplemental Data:
Net assets at end of period	$ 12,773	$ 10,815	$ 12,364	$ 11,872	$ 11,201	$ 10,354	$ 10,049	$ 9,555
Ratio of operating expenses to average net assets	12.45%	12.80%
Ratio of net investment income to average net assets	11.87%	11.95%
Portfolio turnover rate	38.00%	24.00%