South Africa asset impairment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	3 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 South Africa [Member] Write down on Mineral Rights [Member]	Dec. 31, 2013 South Africa [Member] Depreciable Assets [Member]	Sep. 30, 2013 South Africa [Member] Cost of Sales [Member]	Sep. 30, 2013 South Africa [Member] Selling, General and Administrative Expenses [Member]	Sep. 30, 2013 Performance Materials [Member] South Africa [Member]	Sep. 30, 2013 Performance Materials [Member] South Africa [Member] Write down on Mineral Rights [Member]	Sep. 30, 2013 Performance Materials [Member] South Africa [Member] Depreciable Assets [Member]
Impairments [Line Items]
Impairment Charges	$ 59.8	$ 0.9	$ 0.1	$ 36.0	$ 16.3	$ (52.2)	$ (0.1)	$ 52.3	$ (36.0)	$ (16.3)

The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 Accounting Standards Codification

-Topic 230

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-Section 45

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-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 45, 46, 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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