CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Balance at Dec. 31, 2011	$ 219,304	$ 613,831	$ (1,289)	$ (393,238)
Balance (in shares) at Dec. 31, 2011		139,753,000
Increase (Decrease) in Shareholders' Equity
Stock-based compensation	2,845	2,845
Issuance of exchangeable shares to acquire Minera Andes Inc.	664,671	664,671
Issuance of exchangeable shares to acquire Minera Andes Inc. (in shares)		127,331,000
Assumption of stock options in connection with the acquisition of Minera Andes Inc.	3,175	3,175
Exercise of stock options	721	721
Exercise of stock options (in shares)		387,000
Exercise of stock options assumed from Minera Andes Inc. acquisition	2,844	2,844
Exercise of stock options assumed from Minera Andes Inc. acquisition (in shares)		942,000
Shares issued for Mexico mining concessions	391	391
Shares issued for Mexico mining concessions (in shares)		83,000
Unrealized (loss) gain on available-for-sale securities, net of taxes	(2)		(2)
Reclassification of unrealized loss on marketable equity securities disposed of during the period, net of tax	(993)		(993)
Other-than-temporary impairment on marketable equity securities	1,993		1,993
Net loss (adjusted - note 6)	(40,369)			(40,369)
Balance at Sep. 30, 2012	854,580	1,288,478	(291)	(433,607)
Balance (in shares) at Sep. 30, 2012		268,496,000
Balance at Dec. 31, 2012	889,591	1,349,777	(294)	(459,892)
Balance (in shares) at Dec. 31, 2012		296,025,000
Increase (Decrease) in Shareholders' Equity
Stock-based compensation	965	965
Exercise of stock options	95	95
Exercise of stock options (in shares)	48,000	48,000
Exercise of stock options assumed from Minera Andes Inc. acquisition	76	76
Exercise of stock options assumed from Minera Andes Inc. acquisition (in shares)		45,000
Shares issued for litigation settlement	3,270	3,270
Shares issued for litigation settlement (in shares)		1,000,000
Shares issued for Mexico mining concessions	96	96
Shares issued for Mexico mining concessions (in shares)	41,500	41,000
Unrealized (loss) gain on available-for-sale securities, net of taxes	3		3
Net loss (adjusted - note 6)	(136,399)			(136,399)
Balance at Sep. 30, 2013	$ 757,697	$ 1,354,279	$ (291)	$ (596,291)
Balance (in shares) at Sep. 30, 2013		297,159,000