SUBSEQUENT EVENTS (Details) $ in Thousands, oz in Millions	Feb. 06, 2018 oz	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)
Subsequent events
Value of interests		$ 2,810,616	$ 2,892,256
Pascua-Lama
Subsequent events
Value of interests		$ 416,800
Subsequent Event | Pascua-Lama
Subsequent events
Amount of gold reserves | oz	14
Copper NSR (as a percent)	1.09%
Minimum | Subsequent Event | Pascua-Lama
Subsequent events
Gold net smelter return (NSR) (as a percent)	0.78%
Maximum | Subsequent Event | Pascua-Lama
Subsequent events
Gold net smelter return (NSR) (as a percent)	5.45%