EARNINGS PER SHARE ("EPS") (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
EARNINGS PER SHARE ("EPS")
Net income (loss) available to Royal Gold common stockholders	$ 38,554	$ 28,772	$ 150,329	$ 67,368
Net income and comprehensive income available to Royal Gold common stockholders	$ 38,554	$ 28,772	$ 150,329	$ 67,368
Weighted-average shares for basic EPS	65,511,878	65,398,369	65,501,678	65,389,499
Effect of other dilutive securities (in shares)	88,892	116,865	124,722	105,403
Weighted-average shares for diluted EPS	65,600,770	65,515,234	65,626,400	65,494,902
Basic earnings per share (in dollars per share)	$ 0.59	$ 0.44	$ 2.30	$ 1.03
Diluted earnings per share (in dollars per share)	$ 0.59	$ 0.44	$ 2.29	$ 1.03