Consolidated Statements of Changes in Net Assets (Unaudited) - USD ($) $ in Thousands	3 Months Ended									9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023		Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022		Dec. 31, 2021	Sep. 30, 2023	Sep. 30, 2022
Beginning balance	$ 1,460,529	$ 1,356,005	$ 1,341,569		$ 1,241,959	$ 1,283,985	$ 1,275,848			$ 1,341,569	$ 1,275,848
Net investment income	49,994	48,784	42,937		37,180	40,822	35,712			141,714	113,714
Net change in unrealized gain (losses) on investments and foreign currency translation	9,740	2,822	4,777		(5,134)	(54,751)	(8,495)			17,340	(68,379)
Net realized gains (losses) on investments and foreign currency transactions	5,086	1,484	5,238		2,385	404	13,668			$ 11,808	16,456
Issuance of common stock, net of offering and underwriting costs	$ (85)	89,290
Conversion of convertible notes					77,642
Conversion of convertible notes, Shares									2,324,820
Purchases of treasury stock					$ (3,000)						$ (3,000)
Purchases of treasury stock, Shares	0				180,542					0	180,542
Stock issued in connection with dividend reinvestment plan	$ 5,924	5,581	6,248		$ 11,038	5,838	6,774
Stock issued in connection with dividend reinvestment plan, Shares										982,211	1,219,840
Dividends declared from distributable earnings	(45,366)	(43,437)	(44,764)		(34,018)	(34,339)	(39,522)
Ending balance	$ 1,485,822	1,460,529	1,356,005		$ 1,328,052	1,241,959	1,283,985		$ 1,275,848	$ 1,485,822	$ 1,328,052
Ending balance,Shares	87,546,498				81,170,965					87,546,498	81,170,965
Common Stock
Beginning balance	$ 879	$ 824	$ 821		$ 766	$ 764	$ 761			$ 821	$ 761
Beginning balance, Shares	87,241,231	81,751,865	81,389,287		76,339,515	76,070,680	75,771,542			81,389,287	75,771,542
Issuance of common stock, net of offering and underwriting costs		$ 52
Issuance of common stock, net of offering and underwriting costs, Shares		5,175,000
Conversion of convertible notes					$ 44
Conversion of convertible notes, Shares					4,360,125
Purchases of treasury stock, Shares					(180,542)
Stock issued in connection with dividend reinvestment plan	$ 3	$ 3	$ 3		$ 6	$ 2	$ 3
Stock issued in connection with dividend reinvestment plan, Shares	305,267	314,366	362,578		651,867	268,835	299,138
Ending balance	$ 882	$ 879	$ 824		$ 816	$ 766	$ 764		$ 761	$ 882	$ 816
Ending balance,Shares	87,546,498	87,241,231	81,751,865		81,170,965	76,339,515	76,070,680		75,771,542	87,546,498	81,170,965
Treasury Stock
Beginning balance	$ (10,459)	$ (10,459)	$ (10,459)		$ (4,291)	$ (4,291)	$ (4,291)			$ (10,459)	$ (4,291)
Beginning balance, Shares	664,250	664,250	664,250		296,044	296,044	296,044			664,250	296,044
Purchases of treasury stock					$ (3,000)
Purchases of treasury stock, Shares					180,542
Ending balance	$ (10,459)	$ (10,459)	$ (10,459)		$ (7,291)	$ (4,291)	$ (4,291)		$ (4,291)	$ (10,459)	$ (7,291)
Ending balance,Shares	664,250	664,250	664,250		476,586	296,044	296,044		296,044	664,250	476,586
Paid in Capital in Excess of Par
Beginning balance	$ 1,395,409	$ 1,300,593	$ 1,294,751		$ 1,201,531	$ 1,195,695	$ 1,189,275			$ 1,294,751	$ 1,189,275
Issuance of common stock, net of offering and underwriting costs	(85)	89,238
Conversion of convertible notes					77,598
Stock issued in connection with dividend reinvestment plan	5,921	5,578	6,245		11,032	5,836	6,771
Tax reclassification of stockholders' equity in accordance with GAAP			(403)	[1]			(351)	[2]
Ending balance	1,401,245	1,395,409	1,300,593		1,290,161	1,201,531	1,195,695		$ 1,189,275	1,401,245	1,290,161
Distributable Earnings
Beginning balance	74,700	65,047	56,456		43,953	91,817	90,103			56,456	90,103
Net investment income	49,994	48,784	42,937		37,180	40,822	35,712
Net change in unrealized gain (losses) on investments and foreign currency translation	9,740	2,822	4,777		(5,134)	(54,751)	(8,495)
Net realized gains (losses) on investments and foreign currency transactions	5,086	1,484	5,238		2,385	404	13,668
Dividends declared from distributable earnings	(45,366)	(43,437)	(44,764)		(34,018)	(34,339)	(39,522)
Tax reclassification of stockholders' equity in accordance with GAAP			403	[1]			351	[2]
Ending balance	$ 94,154	$ 74,700	$ 65,047		$ 44,366	$ 43,953	$ 91,817		$ 90,103	$ 94,154	$ 44,366

[1] The Company’s tax year end is March 31st.

[2] The Company’s tax year end is March 31st.