Segment Information, Net Sales by Product Categories (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net Sales:
Net sales	$ 338.9	$ 319.9	$ 1,018.1	$ 986.2
Aero/HS products
Net Sales:
Net sales	172.5	163.9	509.1	508.6
GE products
Net Sales:
Net sales	103.6	102.7	323.1	318.7
Automotive Extrusions
Net Sales:
Net sales	44.0	33.8	129.5	95.6
Other products
Net Sales:
Net sales	$ 18.8	$ 19.5	$ 56.4	$ 63.3

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration