CONSOLIDATED STATEMENTS OF CHANGES IN NET ASSETS - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2023	Dec. 31, 2022
Investment Company, Net Assets [Roll Forward]
Beginning balance (in shares)			36,076,425				36,076,425
Beginning balance	$ 657,774	$ 636,201	$ 590,408	$ 475,724	$ 452,985	$ 420,867	$ 590,408	$ 420,867
Beginning balance (in shares)			2,339,512				2,339,512
Issuance of common stock	65,527	22,493	$ 44,872	101,469	26,500	46,035
Cancellation of treasury stock			0
Share-based compensation	1,188	1,236	963	992	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	(138)		(926)	(380)		(641)
Dividends to shareholders	(26,858)	(24,769)	(22,916)	(19,275)	(14,287)	(16,615)
Change in restoration plan liability	(12)	(11)	(12)	8	8	8
Reclassification for certain permanent book-to-tax differences	0			0		0
Net investment income	28,859	27,194	24,556	19,425	14,444	12,438	$ 80,609	46,307
Net realized gain (loss) on investments	(7,842)		(12,782)	(11,086)	(8,635)	2,320	(20,234)	(17,401)
Net realized gain on investments and extinguishment of debt		29
Net unrealized (appreciation) depreciation on investments	$ 2,467	(4,599)	12,038	$ (5,390)	3,649	(12,248)	$ 9,906	$ (13,989)
Ending balance (in shares)	42,981,139			34,559,000			42,981,139	34,559,000
Ending balance	$ 720,965	$ 657,774	$ 636,201	$ 561,487	$ 475,724	$ 452,985	$ 720,965	$ 561,487
Ending balance (in shares)	0						0
Common Stock
Investment Company, Net Assets [Roll Forward]
Beginning balance (in shares)	39,951,118	38,839,918	36,076,425	28,782,062	27,390,741	24,958,520	36,076,425	24,958,520
Beginning balance	$ 9,988	$ 9,710	$ 9,604	$ 7,780	$ 7,433	$ 6,825	$ 9,604	$ 6,825
Issuance of common stock (in shares)	3,036,237	1,100,000	2,527,458	5,799,314	1,381,716	2,262,852
Issuance of common stock	$ 759	$ 275	$ 632	$ 1,450	$ 345	$ 566
Cancellation of treasury stock			$ (585)
Issuance of common stock under restricted stock plan, net of forfeitures (in shares)		11,200	282,616	(2,425)	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)	(6,216)		(46,581)	(19,917)		(29,673)
Common stock withheld for payroll taxes upon vesting of restricted stock	$ (2)		$ (12)	$ (5)		$ (7)
Ending balance (in shares)	42,981,139	39,951,118	38,839,918	34,559,034	28,782,062	27,390,741	42,981,139	34,559,034
Ending balance	$ 10,745	$ 9,988	$ 9,710	$ 9,225	$ 7,780	$ 7,433	$ 10,745	$ 9,225
Treasury Stock
Investment Company, Net Assets [Roll Forward]
Beginning balance	$ 0	$ 0	$ (23,937)	$ (23,937)	$ (23,937)	$ (23,937)	$ (23,937)	$ (23,937)
Beginning balance (in shares)	0	0	2,339,512	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	$ 0	$ (23,937)	$ (23,937)	$ (23,937)	$ 0	$ (23,937)
Ending balance (in shares)	0	0	0	2,339,512	2,339,512	2,339,512	0	2,339,512
Additional Paid-In Capital
Investment Company, Net Assets [Roll Forward]
Beginning balance	$ 690,880	$ 667,440	$ 646,586	$ 521,072	$ 493,851	$ 448,235	$ 646,586	$ 448,235
Issuance of common stock	64,768	22,218	44,240	100,019	26,155	45,469
Cancellation of treasury stock			(23,352)
Share-based compensation	1,188	1,236	963	992	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	(136)		(914)	(375)		(634)
Change in restoration plan liability	(12)	(11)	(12)	8	8	8
Reclassification for certain permanent book-to-tax differences	(5,277)			(5,126)		1
Ending balance	751,411	690,880	667,440	616,590	521,072	493,851	751,411	616,590
Total Distributable Earnings (Loss)
Investment Company, Net Assets [Roll Forward]
Beginning balance	(43,094)	(40,949)	(41,845)	(29,191)	(24,362)	(10,256)	(41,845)	(10,256)
Dividends to shareholders	(26,858)	(24,769)	(22,916)	(19,275)	(14,287)	(16,615)
Reclassification for certain permanent book-to-tax differences	5,277			5,126		(1)
Net investment income	28,859	27,194	24,556	19,425	14,444	12,438
Net realized gain (loss) on investments	(7,842)		(12,782)	(11,086)	(8,635)	2,320
Net realized gain on investments and extinguishment of debt		29
Net unrealized (appreciation) depreciation on investments	2,467	(4,599)	12,038	(5,390)	3,649	(12,248)
Ending balance	$ (41,191)	$ (43,094)	$ (40,949)	$ (40,391)	$ (29,191)	$ (24,362)	$ (41,191)	$ (40,391)