Derivatives and Fair Value Measurements (Details 3) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Explosives Hedge Contracts Member
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	$ (3.0)
Diesel Fuel Hedge Contracts [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	6.0
Fair Value, Measurements, Recurring [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Available-for-sale Securities	69.9	88.4
Total net financial assets	313.4	379.3
Fair Value, Measurements, Recurring [Member] \| Foreign Currency Forward Contract [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	240.5	286.9
Fair Value, Measurements, Recurring [Member] \| Commodity swap contracts [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	3.0	4.0
Fair Value, Measurements, Recurring [Member] \| Level 1[Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Investment in debt and equity securities	59.0	75.4
Total net financial assets	59.0	75.4
Fair Value, Measurements, Recurring [Member] \| Level 1[Member] \| Foreign Currency Forward Contract [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	0	0
Fair Value, Measurements, Recurring [Member] \| Level 1[Member] \| Commodity swap contracts [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	0	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Investment in debt and equity securities	10.9	13.0
Total net financial assets	254.4	303.9
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Foreign Currency Forward Contract [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	240.5	286.9
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Commodity swap contracts [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	3.0	4.0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Investment in debt and equity securities	0	0
Total net financial assets	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Foreign Currency Forward Contract [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Commodity swap contracts [Member]
Fair value of financial asset (liability) positions measured on a recurring basis
Derivative assets (liabilities), at fair value, net	$ 0	$ 0

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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

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

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

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

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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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+ Details

- Definition

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

+ References+ Details

- Definition

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 investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References+ Details