CONSOLIDATED STATEMENTS OF CHANGES IN NET ASSETS - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Investment Company, Net Assets [Roll Forward]
Beginning balance (in shares)		52,912,796			52,912,796
Beginning balance	$ 916,474	$ 883,633	$ 777,331	$ 755,676	$ 883,633	$ 755,676
Issuance of common stock	39,693	41,172	20,237	37,778
Share-based compensation	1,270	1,143	1,538	1,224
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		(1,120)		(1,862)
Dividends to shareholders	(36,040)	(35,344)	(30,520)	(29,508)
Change in restoration plan liability	(12)	(11)	(12)	(12)
Net investment income	31,984	31,889	31,165	28,859	63,873	60,024
Net realized (loss) gain on investments, net of tax	(4,926)	15,704	(10,289)	711	10,778	(9,578)
Net realized loss on investments and disposal of fixed assets	(4,928)
Net unrealized (depreciation) appreciation on investments	$ (1,437)	(20,592)	$ 1,808	(15,535)	$ (22,029)	$ (13,727)
Ending balance (in shares)	56,966,998		47,687,000		56,966,998	47,687,000
Ending balance	$ 947,004	$ 916,474	$ 791,258	$ 777,331	$ 947,004	$ 791,258
Common Stock
Investment Company, Net Assets [Roll Forward]
Beginning balance (in shares)	55,227,370	52,912,796	46,837,511	45,050,759	52,912,796	45,050,759
Beginning balance	$ 13,807	$ 13,228	$ 11,709	$ 11,263	$ 13,228	$ 11,263
Issuance of common stock (in shares)	1,766,975	2,034,917	839,099	1,498,981
Issuance of common stock	$ 442	$ 509	$ 210	$ 375
Issuance of common stock under restricted stock plan, net of forfeitures (in shares)	(27,347)	332,250	10,075	359,000
Issuance of common stock under restricted stock plan, net of forfeitures	$ (7)	$ 83	$ 3	$ 89
Common stock withheld for payroll taxes upon vesting of restricted stock (in shares)		(52,593)		(71,229)
Common stock withheld for payroll taxes upon vesting of restricted stock		$ (13)		$ (18)
Ending balance (in shares)	56,966,998	55,227,370	47,686,685	46,837,511	56,966,998	47,686,685
Ending balance	$ 14,242	$ 13,807	$ 11,922	$ 11,709	$ 14,242	$ 11,922
Treasury Stock
Investment Company, Net Assets [Roll Forward]
Beginning balance	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Beginning balance (in shares)	0	0	0	0	0	0
Ending balance	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Ending balance (in shares)	0	0	0	0	0	0
Additional Paid-In Capital
Investment Company, Net Assets [Roll Forward]
Beginning balance	$ 999,728	$ 959,123	$ 833,627	$ 796,945	$ 959,123	$ 796,945
Issuance of common stock	39,251	40,663	20,027	37,403
Share-based compensation	1,270	1,143	1,538	1,224
Issuance of common stock under restricted stock plan, net of forfeitures	7	(83)	(3)	(89)
Common stock withheld for payroll taxes upon vesting of restricted stock		(1,107)		(1,844)
Change in restoration plan liability	(12)	(11)	(12)	(12)
Ending balance	1,040,244	999,728	855,177	833,627	1,040,244	855,177
Total Distributable Earnings (Loss)
Investment Company, Net Assets [Roll Forward]
Beginning balance	(97,061)	(88,718)	(68,005)	(52,532)	(88,718)	(52,532)
Dividends to shareholders	(36,040)	(35,344)	(30,520)	(29,508)
Net investment income	31,984	31,889	31,165	28,859
Net realized (loss) gain on investments, net of tax		15,704	(10,289)	711
Net realized loss on investments and disposal of fixed assets	(4,928)
Net unrealized (depreciation) appreciation on investments	(1,437)	(20,592)	1,808	(15,535)
Ending balance	$ (107,482)	$ (97,061)	$ (75,841)	$ (68,005)	$ (107,482)	$ (75,841)