CONSOLIDATED STATEMENTS OF CHANGES IN NET ASSETS - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investment Company, Net Assets [Roll Forward]
Beginning balance (in shares)		36,076,425			36,076,425
Beginning balance	$ 636,201	$ 590,408	$ 452,985	$ 420,867	$ 590,408	$ 420,867
Beginning balance (in shares)		2,339,512			2,339,512
Issuance of common stock	22,493	$ 44,872	26,500	46,035
Cancellation of treasury stock		0
Share-based compensation	1,236	963	1,060	821
Issuance of common stock under restricted stock plan, net of forfeitures	0	0	0	0
Common stock withheld for payroll taxes upon vesting of restricted stock		(926)		(641)
Dividends to shareholders	(24,769)	(22,916)	(14,287)	(16,615)
Change in restoration plan liability	(11)	(12)	8	8
Reclassification for certain permanent book-to-tax differences				0
Net investment income	27,194	24,556	14,444	12,438	$ 51,750	26,882
Net realized gain (loss) on investments	390	(12,782)	(8,635)	2,320	(12,392)	(6,315)
Net realized gain on investments and extinguishment of debt	29
Net unrealized (appreciation) depreciation on investments	$ (4,599)	12,038	$ 3,649	(12,248)	$ 7,439	$ (8,599)
Ending balance (in shares)	39,951,118		28,782,000		39,951,118	28,782,000
Ending balance	$ 657,774	$ 636,201	$ 475,724	$ 452,985	$ 657,774	$ 475,724
Ending balance (in shares)	0				0
Common Stock
Investment Company, Net Assets [Roll Forward]
Beginning balance (in shares)	38,839,918	36,076,425	27,390,741	24,958,520	36,076,425	24,958,520
Beginning balance	$ 9,710	$ 9,604	$ 7,433	$ 6,825	$ 9,604	$ 6,825
Issuance of common stock (in shares)	1,100,000	2,527,458	1,381,716	2,262,852
Issuance of common stock	$ 275	$ 632	$ 345	$ 566
Cancellation of treasury stock		$ (585)
Issuance of common stock under restricted stock plan, net of forfeitures (in shares)	11,200	282,616	9,605	199,042
Issuance of common stock under restricted stock plan, net of forfeitures	$ 3	$ 71	$ 2	$ 49
Common stock withheld for payroll taxes upon vesting of restricted stock (in shares)		(46,581)		(29,673)
Common stock withheld for payroll taxes upon vesting of restricted stock		$ (12)		$ (7)
Ending balance (in shares)	39,951,118	38,839,918	28,782,062	27,390,741	39,951,118	28,782,062
Ending balance	$ 9,988	$ 9,710	$ 7,780	$ 7,433	$ 9,988	$ 7,780
Treasury Stock
Investment Company, Net Assets [Roll Forward]
Beginning balance	$ 0	$ (23,937)	$ (23,937)	$ (23,937)	$ (23,937)	$ (23,937)
Beginning balance (in shares)	0	2,339,512	2,339,512	2,339,512	2,339,512	2,339,512
Cancellation of treasury stock (in shares)		(2,339,512)
Cancellation of treasury stock		$ 23,937
Ending balance	$ 0	$ 0	$ (23,937)	$ (23,937)	$ 0	$ (23,937)
Ending balance (in shares)	0	0	2,339,512	2,339,512	0	2,339,512
Additional Paid-In Capital
Investment Company, Net Assets [Roll Forward]
Beginning balance	$ 667,440	$ 646,586	$ 493,851	$ 448,235	$ 646,586	$ 448,235
Issuance of common stock	22,218	44,240	26,155	45,469
Cancellation of treasury stock		(23,352)
Share-based compensation	1,236	963	1,060	821
Issuance of common stock under restricted stock plan, net of forfeitures	(3)	(71)	(2)	(49)
Common stock withheld for payroll taxes upon vesting of restricted stock		(914)		(634)
Change in restoration plan liability	(11)	(12)	8	8
Reclassification for certain permanent book-to-tax differences				1
Ending balance	690,880	667,440	521,072	493,851	690,880	521,072
Total Distributable Earnings (Loss)
Investment Company, Net Assets [Roll Forward]
Beginning balance	(40,949)	(41,845)	(24,362)	(10,256)	(41,845)	(10,256)
Dividends to shareholders	(24,769)	(22,916)	(14,287)	(16,615)
Reclassification for certain permanent book-to-tax differences				(1)
Net investment income	27,194	24,556	14,444	12,438
Net realized gain (loss) on investments		(12,782)	(8,635)	2,320
Net realized gain on investments and extinguishment of debt	29
Net unrealized (appreciation) depreciation on investments	(4,599)	12,038	3,649	(12,248)
Ending balance	$ (43,094)	$ (40,949)	$ (29,191)	$ (24,362)	$ (43,094)	$ (29,191)