EARNINGS PER SHARE ("EPS") (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2011
EARNINGS PER SHARE ("EPS")
Net income available to Royal Gold common stockholders (in dollars)	$ 10,703	$ 6,464	$ 27,216	$ 24,770	$ 20,571	$ 25,999	$ 23,411	$ 22,495	$ 69,153	$ 92,476	$ 71,395
Weighted-average shares for basic EPS									63,250,247	57,220,040	55,053,204
Effect of other dilutive securities (in shares)									179,575	243,810	270,206
Weighted-average shares for diluted EPS									63,429,822	57,463,850	55,323,410
Basic earnings per share (in dollars per share)	$ 0.16	$ 0.10	$ 0.42	$ 0.42	$ 0.35	$ 0.44	$ 0.42	$ 0.41	$ 1.09	$ 1.61	$ 1.29
Diluted earnings per share (in dollars per share)	$ 0.16	$ 0.10	$ 0.42	$ 0.41	$ 0.34	$ 0.44	$ 0.42	$ 0.40	$ 1.09	$ 1.61	$ 1.29
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