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