EARNINGS PER SHARE ("EPS") (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Sep. 30, 2014 USD ($) $ / shares	Jun. 30, 2014 USD ($) $ / shares	Mar. 31, 2014 USD ($) $ / shares	Dec. 31, 2013 USD ($) $ / shares	Sep. 30, 2013 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares shares	Jun. 30, 2014 USD ($) $ / shares shares	Jun. 30, 2013 USD ($) $ / shares shares
EARNINGS PER SHARE ("EPS")
Net income available to Royal Gold (in dollars) | $	$ 14,819	$ 25,014	$ (6,548)	$ 18,680	$ 16,636	$ 20,143	$ 10,667	$ 15,195	$ 51,965	$ 62,641	$ 69,153
Weighted-average shares for basic EPS | shares									65,007,861	64,909,149	63,250,247
Effect of other dilutive securities (in shares) | shares									117,312	117,107	179,575
Weighted-average shares for diluted EPS | shares									65,125,173	65,026,256	63,429,822
Basic earnings per share (in dollars per share)	$ 0.23	$ 0.38	$ (0.10)	$ 0.29	$ 0.26	$ 0.31	$ 0.16	$ 0.23	$ 0.80	$ 0.96	$ 1.09
Diluted earnings per share (in dollars per share)	0.23	$ 0.38	$ (0.10)	$ 0.29	$ 0.26	$ 0.31	$ 0.16	$ 0.23	$ 0.80	$ 0.96	$ 1.09
Exchange ratio for conversion of exchangeable shares of RG Exchangeco into shares of Royal Gold common stock									1
Impact on diluted earnings per share (in dollars per share)									$ 0
2019 Conversion Notes, Initial conversion price per share of common stock (in dollars per share)	$ 105.31								$ 105.31