CONSOLIDATED STATEMENTS OF CHANGES IN NET ASSETS - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Investment Company, Net Assets [Roll Forward]
Number of Shares, beginning balance (in shares)		24,958,520		21,005,000	24,958,520	21,005,000	17,998,000
Beginning balance		$ 420,867		$ 336,251	$ 420,867	$ 336,251	$ 272,222
Number of Shares, beginning balance (in shares)		2,339,512			2,339,512
Issuance of common stock					$ 202,781	98,107	50,393
Share-based compensation					3,705	3,585	2,944
Issuance of common stock under restricted stock plan, net of forfeitures					0	0	0
Common stock withheld for payroll taxes upon vesting of restricted stock					(1,021)	(1,408)	(239)
Dividends to shareholders					(71,102)	(58,624)	(39,945)
Change in restoration plan liability					2,085	141	(7)
Reclassification for certain permanent book-to-tax differences					0	0	0
Net increase in net assets from operations	$ 18,176	$ 2,510	$ 19,669	$ 15,142	$ 33,093	$ 42,815	$ 50,883
Number of Shares, ending balance (in shares)	36,076,425		24,958,520		36,076,425	24,958,520	21,005,000
Ending balance	$ 590,408		$ 420,867		$ 590,408	$ 420,867	$ 336,251
Number of Shares, ending balance (in shares)	2,339,512		2,339,512		2,339,512	2,339,512
Common Stock
Investment Company, Net Assets [Roll Forward]
Number of Shares, beginning balance (in shares)		24,958,520		21,005,324	24,958,520	21,005,324	17,998,098
Beginning balance		$ 6,825		$ 5,836	$ 6,825	$ 5,836	$ 5,085
Issuance of common stock (in shares)					10,969,898	3,872,031	2,810,541
Issuance of common stock					$ 2,742	$ 969	$ 702
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures					197,597	133,289	211,994
Issuance of common stock under restricted stock plan, net of forfeitures					$ 49	$ 33	$ 53
Common stock withheld for payroll taxes upon vesting of restricted stock (in shares)					(49,590)	(52,124)	(15,309)
Common stock withheld for payroll taxes upon vesting of restricted stock					$ (12)	$ (13)	$ (4)
Number of Shares, ending balance (in shares)	36,076,425		24,958,520		36,076,425	24,958,520	21,005,324
Ending balance	$ 9,604		$ 6,825		$ 9,604	$ 6,825	$ 5,836
Treasury Stock
Investment Company, Net Assets [Roll Forward]
Beginning balance		$ (23,937)		$ (23,937)	$ (23,937)	$ (23,937)	$ (23,937)
Number of Shares, beginning balance (in shares)		2,339,512		2,339,512	2,339,512	2,339,512	2,339,512
Ending balance	$ (23,937)		$ (23,937)		$ (23,937)	$ (23,937)	$ (23,937)
Number of Shares, ending balance (in shares)	2,339,512		2,339,512		2,339,512	2,339,512	2,339,512
Additional capital
Investment Company, Net Assets [Roll Forward]
Beginning balance		$ 448,235		$ 356,447	$ 448,235	$ 356,447	$ 310,846
Issuance of common stock					200,039	97,138	49,691
Share-based compensation					3,705	3,585	2,944
Issuance of common stock under restricted stock plan, net of forfeitures					(49)	(33)	(53)
Common stock withheld for payroll taxes upon vesting of restricted stock					(1,009)	(1,395)	(235)
Change in restoration plan liability					2,085	141	(7)
Reclassification for certain permanent book-to-tax differences					6,420	7,648	6,739
Ending balance	$ 646,586		$ 448,235		646,586	448,235	356,447
Total Distributable Earnings (Loss)
Investment Company, Net Assets [Roll Forward]
Beginning balance		$ (10,256)		$ (2,095)	(10,256)	(2,095)	(19,772)
Dividends to shareholders					(71,102)	(58,624)	(39,945)
Reclassification for certain permanent book-to-tax differences					(6,420)	(7,648)	(6,739)
Net increase in net assets from operations					33,093	42,815	50,883
Ending balance	$ (41,845)		$ (10,256)		$ (41,845)	$ (10,256)	$ (2,095)