v3.25.2
SHARE-BASED COMPENSATION - Narrative (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]        
Share‑based compensation $ 5,416 $ 4,883 $ 10,258 $ 8,986
Restricted Stock        
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]        
Share‑based compensation 5,400 $ 4,900 10,300 $ 9,000
Share-based payment arrangement, nonvested award, excluding option, cost not yet recognized, amount $ 46,000   $ 46,000  
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition (in years)     2 years 9 months 18 days  
Restricted Stock | Minimum        
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]        
Vesting period (in years)     3 years  
Restricted Stock | Maximum        
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]        
Vesting period (in years)     5 years  
Restricted Stock | Main Street Capital Corporation 2022 Equity and Incentive Plan | Minimum        
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]        
Vesting period (in years)     3 years  
Restricted Stock | Main Street Capital Corporation 2022 Equity and Incentive Plan | Maximum        
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]        
Vesting period (in years)     5 years