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

SHARE-BASED COMPENSATION - Schedule of Restricted Stock Authorized and Available for Issuance (Details)

v3.25.0.1
SHARE-BASED COMPENSATION - Schedule of Restricted Stock Authorized and Available for Issuance (Details) - Restricted Stock
12 Months Ended
Dec. 31, 2024
shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]  
Less net restricted stock granted (in shares) (522,098)
Main Street Capital Corporation 2022 Equity and Incentive Plan  
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]  
Restricted stock authorized under the plan (in shares) 5,000,000
Less net restricted stock granted (in shares) (1,048,607)
Restricted stock available for issuance (in shares) 3,951,393
Main Street Capital Corporation 2022 Non-Employee Director Restricted Stock Plan | Director  
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]  
Restricted stock authorized under the plan (in shares) 300,000
Less net restricted stock granted (in shares) (11,065)
Restricted stock available for issuance (in shares) 288,935