FINANCIAL INSTRUMENTS: (Tables)

12 Months Ended

Dec. 31, 2013

Schedule of carrying amount and estimated fair values of the Company's financial instruments

Consequently, such financial instruments are not included in the following table that provides information about the carrying amounts and estimated fair values of other financial instruments that are not measured at fair value in the consolidated balance sheet as of December 31, 2013 (in millions):

	Balance at December 31, 2013
	Carrying Value		Fair Value
Liabilities:
Long-term debt	$	4,204.9	$	4,088.8

Schedule of fair values of assets and liabilities measured at fair value on a recurring basis

Fair values of assets and liabilities measured at fair value on a recurring basis were calculated as of December 31, 2013 and 2012, as follows (in millions):

	Fair Value at Measurement Date Using:
Description	Fair Value as of December 31, 2013		Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets:
Short term investment:
- Trading securities	$	202.6	$	202.6
- Available-for-sale debt securities:
Corporate bonds	0.4				$	0.4
Asset backed securities	0.1				0.1
Mortgage backed securities	5.2				5.2

Accounts receivable:
- Derivatives - Not classified as hedges:
Provisionally priced sales:
Copper	53.9		53.9
Molybdenum	100.2		100.2		—		—
Total	$	362.4	$	356.7	$	5.7	$	—

	Fair Value at Measurement Date Using:
Description	Fair Value as of December 31, 2012		Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets:
Short term investment:
- Trading securities	$	127.8	$	127.8
- Available-for-sale debt securities:
Corporate bonds	0.4				$	0.4
Asset backed securities	0.1				0.1
Mortgage backed securities	6.0				6.0

Accounts receivable:
- Derivatives - Not classified as hedges:
Provisionally priced sales:
Copper	70.8		70.8
Molybdenum	102.9		102.9		—		—
Total	$	308.0	$	301.5	$	6.5	$	—

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 15

-Subparagraph b-d

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph c(2), d, e, f

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Subparagraph a, c(1), c(2), c(3), d

-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 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 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 9: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

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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 11: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 19

-Subparagraph a, b, c(1), d(1)

-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.

+ Details