FINANCIAL INSTRUMENTS: (Tables)

3 Months Ended

Mar. 31, 2014

FINANCIAL INSTRUMENTS:

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 condensed consolidated balance sheet as of March 31, 2014 and December 31, 2013 (in millions):

	As of March 31, 2014				As of December 31, 2013
	Carrying Value		Fair Value		Carrying Value		Fair Value
Liabilities:
Long-term debt	$	4,205.2	$	4,233.5	$	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 follows as of March 31, 2014 and December 31, 2013 (in millions):

			Fair Value at Measurement Date Using:
Description	Fair Value as of March 31, 2014		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	$	267.3	$	267.3
- Available for sale debt securities:
Corporate bonds	0.4				$	0.4
Asset backed obligations	0.1				0.1
Mortgage backed securities	5.2				5.2
Accounts receivable:
- Derivatives - Not classified as hedges:
Provisionally priced sales:
Copper	221.3		221.3
Molybdenum	86.7		86.7		—		—
Total	$	581.0	$	575.3	$	5.7	$	—

			Fair Value at Measurement Date Using:
Description	Fair Value as ofDecember 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	$	—