BUSINESS ACQUISITION (Details 2) (USD $)	3 Months Ended		9 Months Ended				3 Months Ended	0 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Jan. 24, 2012	Jun. 30, 2013 Santa Cruz mineral property interests	Jan. 24, 2012 Minera Andes	Sep. 30, 2013 Minera Andes	Dec. 31, 2012 Minera Andes
BUSINESS ACQUISITION
Market price of common stock (in dollars per share)						$ 5.22
Net assets acquired:
Purchase price								$ 667,800,000
Excess of fair value over carrying value of the underlying assets for tax purposes								508,500,000
Deferred income tax recovery related to fluctuations in foreign exchange rates									23,600,000
Deferred income tax recovery							2,300,000
Impairment charges	6,287,000	2,902,000	34,016,000	3,081,000			27,700,000
Deferred income tax liability related to fluctuations in the foreign exchange rates								178,000,000	131,000,000	156,900,000
Deferred income tax liability	$ 198,497,000		$ 198,497,000		$ 229,522,000