FINANCIAL INSTRUMENTS: (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Liabilities:
Long-term debt, Carrying Value	$ 4,204.9	$ 4,213.9
Long-term debt, Fair Value	4,088.8
Fair value measurements recurring \| Fair value as of the end of the period
Short term Investment:
Trading securities investment	202.6	127.8
Derivative:
Total assets, fair value	362.4	308.0
Fair value measurements recurring \| Fair value as of the end of the period \| Copper
Derivative:
Provisionally priced sales	53.9	70.8
Fair value measurements recurring \| Fair value as of the end of the period \| Molybdenum
Derivative:
Provisionally priced sales	100.2	102.9
Fair value measurements recurring \| Fair value as of the end of the period \| Corporate bonds
Available-for-sale debt securities:
Available-for-sale debt securities	0.4	0.4
Fair value measurements recurring \| Fair value as of the end of the period \| Asset backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	0.1	0.1
Fair value measurements recurring \| Fair value as of the end of the period \| Mortgage backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	5.2	6.0
Fair value measurements recurring \| Quoted prices in active markets for identical assets (Level 1)
Short term Investment:
Trading securities investment	202.6	127.8
Derivative:
Total assets, fair value	356.7	301.5
Fair value measurements recurring \| Quoted prices in active markets for identical assets (Level 1) \| Copper
Derivative:
Provisionally priced sales	53.9	70.8
Fair value measurements recurring \| Quoted prices in active markets for identical assets (Level 1) \| Molybdenum
Derivative:
Provisionally priced sales	100.2	102.9
Fair value measurements recurring \| Significant other observable inputs (Level 2)
Derivative:
Total assets, fair value	5.7	6.5
Fair value measurements recurring \| Significant other observable inputs (Level 2) \| Corporate bonds
Available-for-sale debt securities:
Available-for-sale debt securities	0.4	0.4
Fair value measurements recurring \| Significant other observable inputs (Level 2) \| Asset backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	0.1	0.1
Fair value measurements recurring \| Significant other observable inputs (Level 2) \| Mortgage backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	$ 5.2	$ 6.0

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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

-Publisher FASB

-Name Accounting Standards Codification

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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