INCOME TAXES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022
Income Tax Contingency [Line Items]
Dividends	$ 22,900	$ 20,900
Dividends declared (in usd per share)	$ 0.59	$ 0.58
Cost of investments	$ 1,275,400	$ 1,210,800
Gross unrealized appreciation	82,700	72,300
Gross unrealized depreciation	(68,300)	(76,800)
Net unrealized appreciation (depreciation)	14,400	(4,500)
Deferred tax liability	11,855	$ 12,117
Income tax provision	447		$ 192
Excise tax	100		100
RIC
Income Tax Contingency [Line Items]
Cost of investments	1,230,000
Gross unrealized appreciation	17,500
Gross unrealized depreciation	(63,600)
Net unrealized appreciation (depreciation)	(46,100)
Taxable Subsidiary
Income Tax Contingency [Line Items]
Cost of investments	45,400
Gross unrealized appreciation	65,200
Gross unrealized depreciation	(4,700)
Net unrealized appreciation (depreciation)	60,500
Income tax provision	$ 300		$ 100
Regular Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.54	$ 0.53
Supplemental Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.05	$ 0.05