EARNINGS PER SHARE ("EPS") (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
EARNINGS PER SHARE ("EPS")
Net income (loss) available to Royal Gold common stockholders	$ 28,772	$ (153,650)	$ 67,368	$ (139,786)
Weighted-average shares for basic EPS	65,398,369	65,307,324	65,389,499	65,283,019
Effect of other dilutive securities (in shares)	116,865		105,403
Weighted-average shares for diluted EPS	65,515,234	65,307,324	65,494,902	65,283,019
Basic earnings (loss) per share (in dollars per share)	$ 0.44	$ (2.35)	$ 1.03	$ (2.14)
Diluted earnings (loss) per share (in dollars per share)	0.44	$ (2.35)	1.03	$ (2.14)
Initial conversion price (in dollars per share)	$ 102.16		$ 102.16