Main Street Capital Corporation Quarterly report [Sections 13 or 15(d)]

Quarterly report [Sections 13 or 15(d)]

DEBT - Schedule of Debt (Details)

DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024	Mar. 31, 2024
Debt Instrument [Line Items]
Outstanding Balance	$ 2,264,000	$ 2,134,000
Unamortized Debt Issuance (Costs)/ Premiums	(10,821)	(11,629)
Recorded Value	2,253,179	2,122,371
Estimated Fair Value	2,212,533	2,086,717
July 2026 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	500,000	500,000
Unamortized Debt Issuance (Costs)/ Premiums	(680)	(812)
Recorded Value	499,320	499,188
Estimated Fair Value	485,000	482,180
June 2027 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	400,000	400,000
Unamortized Debt Issuance (Costs)/ Premiums	(646)	(718)
Recorded Value	399,354	399,282
Estimated Fair Value	408,428	407,388
March 2029 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	350,000	350,000
Unamortized Debt Issuance (Costs)/ Premiums	(2,818)	(2,998)
Recorded Value	347,182	347,002
Estimated Fair Value	360,339	364,959
SBIC Debentures \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	350,000	350,000	$ 350,000	$ 286,200
Unamortized Debt Issuance (Costs)/ Premiums	(6,289)	(6,583)
Recorded Value	343,711	343,417
Estimated Fair Value	291,517	298,250
December 2025 Notes \| Unsecured Notes
Debt Instrument [Line Items]
Outstanding Balance	150,000	150,000
Unamortized Debt Issuance (Costs)/ Premiums	(388)	(518)
Recorded Value	149,612	149,482
Estimated Fair Value	153,249	149,940
Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Recorded Value	514,000	384,000
Credit Facility \| Corporate Facility \| Line of Credit
Debt Instrument [Line Items]
Outstanding Balance	338,000	208,000
Unamortized Debt Issuance (Costs)/ Premiums	0	0
Recorded Value	338,000	208,000
Estimated Fair Value	338,000	208,000
Credit Facility \| SPV Facility \| Line of Credit
Debt Instrument [Line Items]
Outstanding Balance	176,000	176,000
Unamortized Debt Issuance (Costs)/ Premiums	0	0
Recorded Value	176,000	176,000
Estimated Fair Value	$ 176,000	$ 176,000