COMMITMENTS AND CONTINGENCIES: (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	34 Months Ended
Dec. 31, 2011 person category	Dec. 31, 2012	Dec. 31, 2010
Environmental costs
Environmental capital expenditure	$ 14.0	$ 24.1	$ 16.6
Peruvian operations
Environmental costs
Environmental capital expenditure	2.5	3.4	6.4
Mexican Operations
Environmental costs
Environmental capital expenditure	11.5	20.7	10.2
Number of categories of collective actions	3
Minimum number of people claiming injury due to collective action initiative in Civil Federal Procedures Code (CFPC)	30
Plant demolition and soil remediation budgeted cost		35.7
Plant demolition and soil cost recognized		$ 31.6

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

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

-Publisher AICPA

-Name Statement of Position (SOP)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

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+ Details