BUSINESS ACQUISITION (Details) (Minera Andes, USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	6 Months Ended
Jan. 24, 2012	Jun. 30, 2013
BUSINESS ACQUISITION
Exchange ratio	0.45
Exchangeable Shares received by shareholders of acquiree	127,331,498
Ratio for exchange of exchangeable shares		1
Replacement options
BUSINESS ACQUISITION
Estimated fair value of the vested portion of the replacement options		$ 3.2

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration