STOCKHOLDERS' EQUITY (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		12 Months Ended
	Jun. 30, 2010	Apr. 30, 2009	Jun. 30, 2011	Jun. 30, 2010	Jun. 28, 2010	Apr. 14, 2009
Preferred Stock
Number of authorized and unissued shares (in shares)	10,000,000		10,000,000	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.01		$ 0.01	$ 0.01
Common Stock Issuances
Number of stock options exercised (in shares)			(20,738)	(242,820)
Proceeds from stock options exercised			$ 0.4	$ 1.6
Number of shares of common stock sold in underwritten public offering (in shares)	5,980,000	6,500,000
Offer price of shares of common stock sold in underwritten public offering (in dollars per share)					$ 48.50	$ 38.00
Proceeds from common stock issued, net of commission and expenses	$ 276.2	$ 235.0
Exchangeable Shares
Exchange basis for conversion of exchangeable shares of RG Exchangeco into shares of Royal Gold common stock			one-for-one basis
Number of common shares retired from treasury stock and returned to authorized but unissued amount of common stock (in shares)			96,675
Number of common shares included in treasury stock (in shares)	96,675		0	96,675
Stockholders' Rights Plan
Number of preferred stock purchase rights for each share of Company common stock held			1
Minimum percentage of company's outstanding shares of common stock accumulated by acquiring party for rights to become exercisable (as a percent)			15.00%
Fraction of newly issued share of Series A junior participating preferred stock that could be purchased, for each Right			0.001
Value of a share of the Company's common stock allowed to be purchased for each Right, as a multiple of the exercise price of the Right			Twice
Initial exercise price of the Right (in dollars per right)			$ 175