EARNINGS PER SHARE ("EPS") (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
EARNINGS PER SHARE ("EPS")
Net income available to Royal Gold common stockholders	$ 20,571	$ 25,999	$ 23,411	$ 22,495	$ 21,687	$ 19,565	$ 18,312	$ 11,831	$ 92,476	$ 71,395	$ 21,492
Weighted-average shares for basic EPS									57,220,040	55,053,204	43,640,414
Effect of other dilutive securities (in shares)									243,810	270,206	340,403
Weighted-average shares for diluted EPS									57,463,850	55,323,410	43,980,817
Basic earnings per share (in dollars per share)	$ 0.35	$ 0.44	$ 0.42	$ 0.41	$ 0.39	$ 0.36	$ 0.33	$ 0.22	$ 1.61	$ 1.29	$ 0.49
Diluted earnings per share (in dollars per share)	$ 0.34	$ 0.44	$ 0.42	$ 0.40	$ 0.39	$ 0.35	$ 0.33	$ 0.21	$ 1.61	$ 1.29	$ 0.49
Exchange ratio for conversion of exchangeable shares of RG Exchangeco into shares of Royal Gold common stock									1
2019 Conversion Notes, Initial conversion price per share of common stock (in dollars per share)	$ 105.31								$ 105.31