COMMITMENTS AND CONTINGENCIES: (Details 3) (USD $)		2 Months Ended	12 Months Ended
	Dec. 31, 1997 Y	Jan. 31, 2005 Minera Mexico, S.A. de C.V. (the "Transaction") lawsuit	Dec. 31, 2012 Tia Maria T	Dec. 31, 2012 Tia Maria Peruvian operations
Litigation matter
Number of purported class action derivative lawsuits filed		3
Other commitments:
Estimated annual production of copper cathodes (in tons)			120,000
Term of power purchase agreement related to sale of power plant (in years)	20
Total budget for the project				$ 1,000,000,000
Total spending for the project				480,700,000
Equipment reassigned to other operations, carrying value				$ 176,700,000