Business Segments (Details8) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Inventory valuation reserves	$ 206.3	$ 206.3	$ 68.8
Segment Operating Profit Loss		(84.8)	187.8	$ 11.8
Lifo Provision Benefit and Change in Debit LIFO NRV reserve, net		(0.1)	(0.3)	(45.9)
Corporate expenses		(44.7)	(49.6)	(48.9)
Interest expense, net		(110.2)	(108.7)	(65.2)
Closed company and other expense		(22.1)	(28.3)	(30.9)
Impairment of goodwill		(126.6)	0.0	0.0
Restructuring and other charges		(89.7)	0.0	(67.5)
Income (loss) from continuing operations before income taxes		(478.0)	1.5	(154.8)
Flat Rolled Products [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Impairment of goodwill	$ (126.6)
Operating Segments [Member] \| High Performance Materials & Components [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment Operating Profit Loss		157.1	234.8	159.6
Operating Segments [Member] \| Flat Rolled Products [Member]
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Segment Operating Profit Loss		$ (241.9)	$ (47.0)	$ (147.8)

corporate office expenses not allocable to business segments

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Net interest expense - the cost of borrowed funds as interest charged against earnings during the period net of interest income derived from investments in debt securities and on cash and cash equivalents.

+ References

No definition available.

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- Definition

Lifo Provision Benefit and Change in Debit LIFO NRV reserve, net

+ References

No definition available.

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- Definition

Other expense, net of gains on asset sales primarily includes charges incurred in connection with closed operations and other non-operating income or expense

+ References

No definition available.

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- Definition

Restructuring and other charges

+ References

No definition available.

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- Definition

Business segment operating profit, which excludes costs for restructuring charges, retirement benefit income or expense, corproate expenses, interest expense, debt extinguishment costs and costs associated with closed operations. These costs are excluded for segment reporting to provide a profit measure based on what management considers to be controllable costs at the business segment level

+ References

No definition available.

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- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (b)
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- Definition

This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 20
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-Paragraph 1
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 10
-Article 5

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- Definition

Amount of valuation reserve for inventory.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
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-Paragraph 2
-Subparagraph (SAB TOPIC 5.BB)
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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