Pension Plans and Other Postretirement Benefits (Details17) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	$ 3.5	$ 0.9	$ 1.0
Description Of Multiemployer Plan	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, 2011, 2010 and 2009 is reported in the following table. Participation with regard to multiemployer plans involving ATI Ladish is included from the May 9, 2011 acquisition date.
Multiemployer Plan, Significant Changes Impacting Comparability	Red The most recent Pension Protection Act Zone Status available for ATI’s fiscal years 2011 and 2010 is for plan years ending in calendar years 2010 and 2009, respectively. The zone status is based on information provided to ATI and other participating employers by each plan and is certified by the plan’s actuary. A plan in the “red” zone had been determined to be in “critical status”, based on criteria established by the Internal Revenue Code (“Code”), and is generally less than 65% funded. A plan in the “yellow” zone has been determined to be in “endangered status”, based on criteria established under the Code, and is generally less than 80% funded. A plan in the “green” zone has been determined to be neither in “critical status” nor in “endangered status”, and is generally at least 80% funded. The “FIP / FP status Pending / Implemented” column indicates whether a Funding Improvement Plan, as required under the Code by plans in the “yellow” zone, or a Rehabilitation Plan, as required under the Code to be adopted by plans in the “red” zone, is pending or has been implemented as of the end of the plan year that ended in 2011. The “Surcharge Imposed” column indicates whether ATI’s contribution rate for 2011 included an amount in addition to the contribution rate specified in the applicable collective bargaining agreement, as imposed by a plan in “critical status”, in accordance with the requirements of the Code. The Company is party to six separate bargaining agreements that require contributions to this plan. Expiration dates of these collective bargaining agreements range between July 14, 2014 and July 14, 2019. The Company’s contributions to the Steelworkers Western Independent Shops Pension Plan exceeds 5% of this plan’s total contributions for the most recent fiscal year.
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	1.2	0.9	1.0
Steelworkers Western Independent Shops Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	1.2	0.9	1.0
Description Of Multiemployer Plan	Steelworkers Western Independent Shops Pension Plan 90-0169564 / 001
Multiemployer Plan, Significant Changes Impacting Comparability		Red
Collective Bargaining Agreement Expiration Date	Jun. 30, 2015
Boilermakers-Blacksmiths National Pension Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	1.2
Description Of Multiemployer Plan	Boilermakers- Blacksmiths National Pension Trust 48-6168020 / 001
Multiemployer Plan, Significant Changes Impacting Comparability	Yellow
Collective Bargaining Agreement Expiration Date	Oct. 30, 2018
IAM National Pension Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plan Period Contributions	$ 1.1	$ 0	$ 0
Description Of Multiemployer Plan	IAM National Pension Fund 51-6031295 / 002
Multiemployer Plan, Significant Changes Impacting Comparability	Green	Green
IAM National Pension Fund [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Collective Bargaining Agreement Expiration Date	Jul. 14, 2019
IAM National Pension Fund [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Collective Bargaining Agreement Expiration Date	Jul. 14, 2014