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INCOME TAXES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024
Income Tax Contingency [Line Items]
Dividends	$ 30,500	$ 29,500	$ 28,400
Dividends declared (in usd per share)	$ 0.64	$ 0.63	$ 0.63
Cost of investments	$ 1,538,100		$ 1,471,100
Gross unrealized appreciation	96,000		96,300
Gross unrealized depreciation	125,600		96,400
Net unrealized appreciation (depreciation)	(29,600)		100
Total net deferred tax (liabilities) assets	(12,590)		$ (11,997)
RIC
Income Tax Contingency [Line Items]
Cost of investments	1,485,600
Gross unrealized appreciation	15,500
Gross unrealized depreciation	115,100
Net unrealized appreciation (depreciation)	(99,600)
Taxable Subsidiary
Income Tax Contingency [Line Items]
Cost of investments	52,500
Gross unrealized appreciation	80,500
Gross unrealized depreciation	10,500
Net unrealized appreciation (depreciation)	$ 70,000
O 2025 Q2 Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.58
S 2025 Q2 Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)	$ 0.06
O 2025 Q1 Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)		0.57
S 2025 Q1 Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)		$ 0.06
O 2024 Q4 Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)			$ 0.57
S 2024 Q4 Dividends
Income Tax Contingency [Line Items]
Dividends declared (in usd per share)			$ 0.06