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BUSINESS ACQUISITION (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended			1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jan. 31, 2012 Minera Andes	Jun. 30, 2012 Minera Andes	Jan. 31, 2012 Minera Andes Replacement options	Jun. 30, 2012 Minera Andes Replacement options	Jun. 30, 2011 Minera Andes Robert R. McEwen	Jun. 30, 2012 Minera Andes Robert R. McEwen	Jan. 31, 2012 Minera Andes McEwen Mining
BUSINESS ACQUISITION
Exchange ratio			0.45
2012 Exchangeable Shares received by shareholders of acquiree			127,331,498				38,700,000
Shareholding of combined company (as a percent)			48.00%						52.00%
Shareholding of combined company on a diluted basis (as a percent)			47.00%						53.00%
Percentage of shares of the company owned								25.10%
Ratio for exchange of 2012 exchangeable shares				1
Estimated fair value of the vested portion of the replacement options						$ 3.2
Principal assumptions used in applying the Black-Scholes option pricing model
Risk-free interest rate, low end of range (as a percent)		2.33%			0.02%
Risk-free interest rate, high end of range (as a percent)		3.09%			0.39%
Volatility factor of the expected market price of common stock, low end of range (as a percent)		90.00%			46.00%
Volatility factor of the expected market price of common stock, high end of range (as a percent)		99.00%			77.00%
Weighted-average expected life of option	6 years	6 years 7 months 6 days			1 year 4 months 24 days

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Represents the percentage of ownership interest held by the entity after the acquisition.

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Represents the percentage of ownership interest on diluted basis held by the entity after the acquisition.

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Represents the number of shares of common stock into which each unit of another convertible security can be converted.

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Number of shares of exchangeable stock issued during the period pursuant to acquisitions.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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

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