Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Variable Interest Entity [Line Items]
Income (loss) before income taxes	$ (69.4)	$ 4.0
SunCoke Middletown [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Expected Production Of Coke (in tons)	550,000
Expected Production Of Electricity (in MWs)	45
Variable interest entity, ownership percentage (in hundredths)	0.00%
Income (loss) before income taxes	$ 15.0	$ 16.9
Vicksmetal Armco Associates [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable interest entity, ownership percentage (in hundredths)	50.00%

Expected annual production of coke from a production facility

No definition available.

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Namespace Prefix:	aks_
Data Type:	num:massItemType
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- Definition

Expected annual production of electricity from a production facility

+ References

No definition available.

+ Details

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Namespace Prefix:	aks_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- 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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 10

-Article 5

+ Details

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

- Details

Name:	us-gaap_VariableInterestEntityLineItems
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- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 5A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=28200181&loc=SL6759159-111685

+ Details

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Period Type:	duration