INVESTMENT IN SEABRIDGE GOLD, INC. AND ACQUSITION OF A ROYALTY OPTION ON THE KERR-SULPHURETS-MITCHELL PROJECT (Details)	12 Months Ended	1 Months Ended				1 Months Ended
	Jun. 30, 2011 USD ($)	Jun. 30, 2011 Seabridge	Jun. 30, 2011 Seabridge Initial Shares CAD	Jun. 30, 2011 Seabridge Initial Shares USD ($)	Jun. 16, 2011 Seabridge Initial Shares	Jun. 30, 2011 Seabridge Subsequent Shares CAD	Jun. 30, 2011 Seabridge Initial Royalty CAD	Jun. 30, 2011 Seabridge Increased Royalty CAD
Investment in Seabridge Gold, Inc. and acquisition of a royalty option on the Kerr-Sulphurets-Mitchell project
Common shares acquired in a private placement (in shares)			1,019,000	1,019,000
Approximate percentage of common stock acquired (as a percent)					2.00%
Payment made for common shares acquired	$ 28,574,000		30,000,000	$ 30,700,000
Payment made for common shares acquired (in dollars per share)			29.44	$ 30.14
Premium on share price as a percentage to the volume weighted-average trading price of common shares (as a percent)			15.00%	15.00%		15.00%
Trading period used to calculate premium on share price (in days)			5	5
Holding period of shares as a condition to acquire royalty (in days)			270	270		270
Percentage of royalty that can be acquired (as a percent)							1.25%	2.00%
Purchase price of royalty							100,000,000	60,000,000
Number of installments in which the purchase price of royalty is payable							3	3
Installment period in which the purchase price of royalty is payable (in days)							540	540
Maximum amount of additional common shares that can be acquired						18,000,000
Exercisable period to acquire the Initial Royalty and the Increased Royalty (in days)		60