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EQUITY METHOD INVESTMENTS - Summary of the operating results of McEwen Copper (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
EQUITY METHOD INVESTMENTS      
Advanced projects $ (4,779) $ (1,684)  
Interest and other income (expenses) (1,537) (1,286)  
Income (loss) before income and mining taxes 33,205 (7,349)  
Net income (loss) and comprehensive income (loss) attributable to McEwen shareholders     $ (1,259)
Income (loss) from equity method investment 30,338 (8,068)  
McEwen Copper Inc.      
EQUITY METHOD INVESTMENTS      
Net income (loss) and comprehensive income (loss) attributable to McEwen shareholders (2,057) (8,578)  
McEwen Inc.'s portion of interest capitalized (17)    
Income (loss) from equity method investment $ (2,074) $ (8,578)  
McEwen Copper Inc.      
EQUITY METHOD INVESTMENTS      
Subsidiary (as a percent) 100.00% 100.00%  
Advanced projects   $ (21,271)  
Other expenses $ (2,900) (1,097)  
Foreign exchange gain (loss) 177 (9)  
Interest and other income (expenses) (1,720) 3,906  
Income (loss) before income and mining taxes (4,443) (18,471)  
Net income (loss) and comprehensive income (loss) attributable to McEwen shareholders $ (4,443) $ (18,471)