BORROWINGS - Narrative (Details)							1 Months Ended	3 Months Ended		9 Months Ended
	Dec. 09, 2024 USD ($)	Nov. 04, 2024 USD ($) tradingDay $ / shares	Mar. 20, 2024 USD ($)	Mar. 01, 2024	Aug. 02, 2023 USD ($)	Apr. 20, 2021 USD ($)	Aug. 31, 2021 USD ($)	Dec. 31, 2024 USD ($) facility $ / shares	Dec. 31, 2023 USD ($)	Dec. 31, 2024 USD ($) consecutiveTradingDay facility $ / shares	Dec. 31, 2023 USD ($)	Sep. 12, 2024 USD ($) lender	Sep. 11, 2024 USD ($)	Jun. 20, 2024 USD ($)	Jun. 19, 2024 USD ($)	Dec. 20, 2023 USD ($)	Dec. 07, 2023 USD ($) lender	Dec. 06, 2023 USD ($)	Aug. 01, 2023 USD ($)	Jun. 30, 2023 USD ($)	Nov. 22, 2022 USD ($)	Jan. 28, 2022 USD ($)	Nov. 30, 2021 USD ($)	May 25, 2021 USD ($)	Feb. 28, 2021 USD ($)	Dec. 31, 2020 USD ($)	Apr. 25, 2019
Debt Instrument [Line Items]
Asset coverage ratio																											166.00%
Current asset coverage ratio								209.00%		209.00%
January 2026 Notes | Notes
Debt Instrument [Line Items]
Weighted average effective interest rate								4.46%	4.46%	4.46%	4.46%
Aggregate principal amount																									$ 65,000,000	$ 75,000,000
Fixed interest rate																										4.50%
Issuance price percent received																									102.11%
Yield-to-maturity																									4.00%
Repurchased face amount	$ 140,000,000
Redemption price, percentage	100.00%
Realized loss on disposal of fixed assets								$ (400,000)
October 2026 Notes | Notes
Debt Instrument [Line Items]
Weighted average effective interest rate								3.50%	3.50%	3.50%	3.50%
Aggregate principal amount							$ 100,000,000																$ 50,000,000
Fixed interest rate							3.375%																3.375%
Issuance price percent received							99.418%																99.993%
Yield-to-maturity							3.50%																3.375%
Redemption price, percentage							100.00%
October 2026 Notes | Convertible Debt
Debt Instrument [Line Items]
Fixed interest rate		5.125%
August 2028 Notes | Notes
Debt Instrument [Line Items]
Weighted average effective interest rate								7.75%	7.75%	7.75%	7.75%
Aggregate principal amount																				$ 71,900,000
Fixed interest rate																				7.75%
August 2028 Notes Overallotment | Notes
Debt Instrument [Line Items]
Aggregate principal amount																				$ 9,400,000
SBA Debentures | Unsecured Debt
Debt Instrument [Line Items]
Weighted average effective interest rate								4.40%	4.24%	4.39%	4.13%
SBA Debentures | Unsecured Debt | SBIC I
Debt Instrument [Line Items]
Maturity						10 years
Regulatory maximum borrowing capacity						$ 175,000,000
Regulatory capital						$ 87,500,000		$ 87,500,000		$ 87,500,000
Leverage commitment amount								175,000,000		175,000,000						$ 45,000,000					$ 50,000,000	$ 40,000,000		$ 40,000,000
Available leverage commitment								$ 87,500,000		$ 87,500,000
2029 Convertible Notes | Convertible Debt
Debt Instrument [Line Items]
Weighted average effective interest rate								5.13%	0.00%	5.13%	0.00%
Aggregate principal amount		$ 230,000,000
Fixed interest rate		5.125%
Redemption price, percentage										100.00%
Conversion rate		0.04								40.09
Conversion price (in usd per share) | $ / shares		$ 25.00						$ 24.94		$ 24.94
Dividend increase (in usd per share) | $ / shares								$ 0.58		$ 0.58
Percentage of stock price		130.00%
Trading days | tradingDay		20
Consecutive trading days | consecutiveTradingDay										30
2029 Convertible Notes | Convertible Debt | Maximum
Debt Instrument [Line Items]
Conversion rate										0.0447828
2029 Convertible Notes Overallotement | Convertible Debt
Debt Instrument [Line Items]
Aggregate principal amount		$ 30,000,000
Corporate Credit Facility | Line of Credit
Debt Instrument [Line Items]
Weighted average effective interest rate								7.20%		7.54%
Average borrowings								$ 283,900,000		$ 190,300,000
Corporate Credit Facility | Corporate Credit Facility | Line of Credit
Debt Instrument [Line Items]
Number of revolving credit facility | facility								1		1
Weighted average effective interest rate								7.19%	7.88%	7.53%	7.61%
Average borrowings								$ 179,511,000	$ 224,728,000	$ 134,665,000	$ 162,915,000
Basis spread on variable rate					2.15%
Maximum borrowing capacity					$ 435,000,000							$ 485,000,000	$ 460,000,000				$ 460,000,000	$ 435,000,000	$ 400,000,000
Accordion feature increase limit					$ 750,000,000							$ 25,000,000					$ 25,000,000
Number of lenders | lender												11					10
Minimum senior coverage ratio				2.00
Maximum asset coverage ratio				1.50
Interest coverage ratio				2.00
Corporate Credit Facility | Corporate Credit Facility | Line of Credit | Minimum
Debt Instrument [Line Items]
Commitment fee percentage				0.50%
Corporate Credit Facility | Corporate Credit Facility | Line of Credit | Maximum
Debt Instrument [Line Items]
Commitment fee percentage				1.00%
Secured Debt | SPV Credit Facility | Line of Credit
Debt Instrument [Line Items]
Number of revolving credit facility | facility								1		1
Weighted average effective interest rate								7.23%	0.00%	7.54%	0.00%
Average borrowings								$ 104,435,000	$ 0	$ 55,664,000	$ 0
Maximum borrowing capacity			$ 150,000,000												$ 150,000,000
Accordion feature increase limit														$ 200,000,000
Accordion feature that allows increases (up to)			$ 400,000,000
Secured Debt | SPV Credit Facility | Line of Credit | Before March 20 2027
Debt Instrument [Line Items]
Basis spread on variable rate			2.50%
Secured Debt | SPV Credit Facility | Line of Credit | After March 20 2027
Debt Instrument [Line Items]
Basis spread on variable rate			2.85%
Secured Debt | SPV Credit Facility | Line of Credit | Before April 20 2024
Debt Instrument [Line Items]
Commitment fee percentage			0.10%
Secured Debt | SPV Credit Facility | Line of Credit | After April 20 2024
Debt Instrument [Line Items]
Commitment fee percentage			0.35%