INCOME TAXES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024
Income Tax Contingency [Line Items]
Dividends	$ 29,500	$ 28,400
Dividends declared (in usd per share)	$ 0.63	$ 0.63
Cost of investments	$ 1,475,700	$ 1,471,100
Gross unrealized appreciation	98,000	96,300
Gross unrealized depreciation	111,300	96,400
Net unrealized appreciation (depreciation)	(13,300)	100
Total net deferred tax (liabilities) assets	(13,944)	$ (11,997)
RIC
Income Tax Contingency [Line Items]
Cost of investments	1,432,400
Gross unrealized appreciation	16,000
Gross unrealized depreciation	101,400
Net unrealized appreciation (depreciation)	(85,400)
Taxable Subsidiary
Income Tax Contingency [Line Items]
Cost of investments	43,300
Gross unrealized appreciation	82,000
Gross unrealized depreciation	9,900
Net unrealized appreciation (depreciation)	$ 72,100
Regular Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.57	$ 0.57
Supplemental Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.06	$ 0.06