Main Street Capital Corporation Annual report [Section 13 and 15(d), not S-K Item 405]

Annual report [Section 13 and 15(d), not S-K Item 405]

DEBT - Schedule of Debt (Details)

DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Sep. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Outstanding Balance	$ 2,134,000			$ 1,810,000
Unamortized Debt Issuance (Costs)/ Premiums	(11,629)			(7,656)
Recorded Value	2,122,371			1,802,344
Estimated Fair Value	2,086,717			1,704,974
July 2026 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	500,000			500,000
Unamortized Debt Issuance (Costs)/ Premiums	(812)			(1,338)
Recorded Value	499,188			498,662
Estimated Fair Value	482,180			458,105
June 2027 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	400,000
Unamortized Debt Issuance (Costs)/ Premiums	(718)
Recorded Value	399,282			0
Estimated Fair Value	407,388
March 2029 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	350,000
Unamortized Debt Issuance (Costs)/ Premiums	(2,998)
Recorded Value	347,002			0
Estimated Fair Value	364,959
May 2024 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance				450,000
Unamortized Debt Issuance (Costs)/ Premiums				182
Recorded Value	0			450,182
Estimated Fair Value				447,246
SBIC Debentures \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	350,000	$ 350,000	$ 286,200	350,000
Unamortized Debt Issuance (Costs)/ Premiums	(6,583)			(5,465)
Recorded Value	343,417			344,535
Estimated Fair Value	298,250			288,468
December 2025 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	150,000			150,000
Unamortized Debt Issuance (Costs)/ Premiums	(518)			(1,035)
Recorded Value	149,482			148,965
Estimated Fair Value	149,940			151,155
Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Recorded Value	384,000			360,000
Credit Facility \| Corporate Facility \| Line of Credit
Debt Instrument [Line Items]
Outstanding Balance	208,000			200,000
Unamortized Debt Issuance (Costs)/ Premiums	0			0
Recorded Value	208,000			200,000
Estimated Fair Value	208,000			200,000
Credit Facility \| SPV Facility \| Line of Credit
Debt Instrument [Line Items]
Outstanding Balance	176,000			160,000
Unamortized Debt Issuance (Costs)/ Premiums	0			0
Recorded Value	176,000			160,000
Estimated Fair Value	$ 176,000			$ 160,000