Pension Plans and Other Postretirement Benefits (Details17) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Multiemployer Plan Disclosure [Line Items]
MultiemployerPlansGeneralNature	The Company contributes to several multiemployer defined benefit pension plans under collective bargaining agreements that cover certain of its union-represented employees. The risks of participating in such plans are different from the risks of single-employer plans, in the following respects: Assets contributed to a multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. If a participating employer ceases to contribute to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers. If the Company ceases to have an obligation to contribute to the multiemployer plan in which it had been a contributing employer, it may be required to pay to the plan an amount based on the underfunded status of the plan and on the history of the Company’s participation in the plan prior to the cessation of its obligation to contribute. The amount that an employer that has ceased to have an obligation to contribute to a multiemployer plan is required to pay to the plan is referred to as a withdrawal liability. The Company’s participation in multiemployer plans for the years ended December 31, 2012, 2011 and 2010 is reported in the following table. Participation with regard to multiemployer plans involving ATI Ladish is included from the May 9, 2011 acquisition date.
Pension Benefits [Member]
Multiemployer Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	$ 5.6	$ 3.5	$ 0.9
Steelworkers Western Independent Shops Pension Plan [Member] \| Pension Benefits [Member]
Multiemployer Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	1.3	1.2	0.9
EntityTaxIdentificationNumber	900169564
MultiemployerPlanNumber	001
MultiemployerPlansCertifiedZoneStatus	Red	Red
MultiemployerPlansFundingImprovementPlanAndRehabilitationPlan	Implemented
MultiemployerPlansCollectiveBargainingArrangementExpirationDate	Jun. 30, 2015
MultiemployerPlansSurcharge	No
Boilermakers-Blacksmiths National Pension Trust [Member] \| Pension Benefits [Member]
Multiemployer Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	2.4	1.2	0
EntityTaxIdentificationNumber	486168020
MultiemployerPlanNumber	001
MultiemployerPlansCertifiedZoneStatus	Yellow	Yellow
MultiemployerPlansFundingImprovementPlanAndRehabilitationPlan	Implemented
MultiemployerPlansCollectiveBargainingArrangementExpirationDate	Oct. 30, 2018
MultiemployerPlansSurcharge	No
IAM National Pension Fund [Member] \| Pension Benefits [Member]
Multiemployer Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	$ 1.9	$ 1.1	$ 0
EntityTaxIdentificationNumber	516031295
MultiemployerPlanNumber	002
MultiemployerPlansCertifiedZoneStatus	Green	Green
MultiemployerPlansFundingImprovementPlanAndRehabilitationPlan	NA
MultiemployerPlansCollectiveBargainingArrangementExpirationDateFirst	Jul. 14, 2014
MultiemployerPlansCollectiveBargainingArrangementExpirationDateLast	Jul. 14, 2019
MultiemployerPlansSurcharge	No

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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

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Three digit plan number for a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Indicate the multiemployer plan's certified zone status as currently required by the Pension Protection Act of 2006 or a subsequent amendment thereof. The zone status categories are red (critical status), orange (seriously endangered), yellow (endangered), and green (none of the above). The acceptable values are "red", "orange", "yellow", "green", "other", and "NA". A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Expiration date of the collective bargaining arrangement requiring contributions to the multiemployer plan, in CCYY-MM-DD format. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Expiration date of the collective bargaining arrangement requiring contributions to the multiemployer plan that will expire first in a group of associated collective bargaining arrangements, in CCYY-MM-DD format. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Expiration date of the collective bargaining arrangement requiring contributions to the multiemployer plan that will expire last in a group of associated collective bargaining arrangements, in CCYY-MM-DD format. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Indicate whether a funding improvement plan or rehabilitation plan has been implemented or is pending for a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. The acceptable values are "no", "pending", "implemented", "other", and "NA".

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Description of the general nature of multiemployer plans and of the employer's participation in those plans that would indicate how the risks of participating in these plans are different from single-employer plans. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Indicate whether the employer paid a surcharge to the pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. The acceptable values are "no", "yes", and "NA".

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