Segment Information, Net Sales by Product Categories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net Sales:
Net sales	$ 328.9	$ 345.2	$ 666.3	$ 710.6
Aero/HS Products
Net Sales:
Net sales	165.1	170.9	344.7	355.6
GE Products
Net Sales:
Net sales	110.2	113.5	216.0	232.7
Automotive Extrusions
Net Sales:
Net sales	31.0	33.1	61.8	67.5
Other Products
Net Sales:
Net sales	$ 22.6	$ 27.7	$ 43.8	$ 54.8

Amount of revenue from external customers for the reportable segment. Such disclosure is presented if the amount is: (a) included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration