INCOME TAXES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					9 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Income Tax Contingency [Line Items]
Dividends	$ 26,900	$ 24,800	$ 22,900	$ 20,900
Dividends declared (in usd per share)	$ 0.63	$ 0.62	$ 0.59	$ 0.58
Undistributed ordinary income - tax basis	$ 22,200					$ 22,200
Cumulative undistributed taxable income (in usd per share)	$ 0.52					$ 0.52
Cost of investments	$ 1,350,200			$ 1,210,800		$ 1,350,200
Gross unrealized appreciation	86,800			72,300		86,800
Gross unrealized depreciation	72,000			76,800		72,000
Net unrealized appreciation (depreciation)	14,800			(4,500)		14,800
Deferred tax liability	10,925			$ 12,117		10,925
Income tax provision (benefit)	907				$ (746)	571	$ (20)
Excise tax	400				200	590	468
RIC
Income Tax Contingency [Line Items]
Cost of investments	1,305,800					1,305,800
Gross unrealized appreciation	18,600					18,600
Gross unrealized depreciation	68,000					68,000
Net unrealized appreciation (depreciation)	(49,400)					(49,400)
Taxable Subsidiary
Income Tax Contingency [Line Items]
Cost of investments	44,400					44,400
Gross unrealized appreciation	68,200					68,200
Gross unrealized depreciation	4,000					4,000
Net unrealized appreciation (depreciation)	64,200					64,200
Income tax provision (benefit)	$ 500				$ (900)	$ (100)	$ (500)
Regular Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.57	0.56	0.54	$ 0.53
Supplemental Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.06	$ 0.06	$ 0.05	$ 0.05