OPERATING SEGMENT REPORTING - Geographic information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues from External Customers and Long-Lived Assets
Non-current Assets	$ 604,578				$ 447,066				$ 604,578	$ 447,066
Revenue	58,680	$ 38,404	$ 34,395	$ 34,752	28,240	$ 25,988	$ 30,647	$ 25,542	166,231	110,417	$ 136,541
Investment in MSC	326,147								326,147
Minera Santa Cruz S.A.
Revenues from External Customers and Long-Lived Assets
Revenue									254,926	254,698	271,863
Investment in MSC	93,218				93,451				93,218	93,451	90,961
Asahi Refining Inc.
Revenues from External Customers and Long-Lived Assets
Revenue									24,639	57,835	134,395
USA
Revenues from External Customers and Long-Lived Assets
Non-current Assets	71,234				70,577				71,234	70,577
Revenue									83,409	47,926	79,205
Canada
Revenues from External Customers and Long-Lived Assets
Non-current Assets	83,674				91,552				83,674	91,552
Revenue									81,295	60,848	50,704
Mexico
Revenues from External Customers and Long-Lived Assets
Non-current Assets	30,304				29,219				30,304	29,219
Revenue									1,527	1,643	$ 6,632
Argentina
Revenues from External Customers and Long-Lived Assets
Non-current Assets	419,366				255,718				419,366	255,718
Argentina | Minera Santa Cruz S.A.
Revenues from External Customers and Long-Lived Assets
Investment in MSC	93,200				93,500				93,200	93,500
Argentina | McEwen Copper Inc.
Revenues from External Customers and Long-Lived Assets
Investment in MSC	$ 326,100				$ 0				$ 326,100	$ 0