EARNINGS PER SHARE ("EPS") (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
EARNINGS PER SHARE ("EPS")
Net (loss) income attributable to Royal Gold stockholders	$ (153,650)	$ 23,661	$ (139,786)	$ 81,509
Weighted-average shares for basic EPS	65,307,324	65,169,883	65,283,019	65,145,183
Effect of other dilutive securities (in shares)		105,043		122,018
Weighted-average shares for diluted EPS	65,307,324	65,274,926	65,283,019	65,267,201
Basic (loss) earnings per share (in dollars per share)	$ (2.35)	$ 0.36	$ (2.14)	$ 1.25
Diluted (loss) earnings per share (in dollars per share)	(2.35)	$ 0.36	(2.14)	$ 1.25
Initial conversion price (in dollars per share)	$ 102.67		$ 102.67