ATI (ATI) 10-Q 31 Oct 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	9 Months Ended
	Sep. 30, 2014	Oct. 24, 2014	Jun. 30, 2013
Document And Entity Information [Abstract]	'	'	'
Document Type	'10-Q	'	'
Document Period End Date	30-Sep-14	'	'
Amendment Flag	'false	'	'
Entity Registrant Name	'ALLEGHENY TECHNOLOGIES INCORPORATED	'	'
Entity Central Index Key	'0001018963	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Common Stock, Shares Outstanding	'	108,702,948	'
Document Fiscal Year Focus	'2014	'	'
Document Fiscal Period Focus	'Q3	'	'
Entity Public Float	'	'	$2,800,000,000

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current Assets:	'	'
Cash and cash equivalents	$264.20	$1,026.80
Accounts receivable, net of allowances for doubtful accounts of $4.8 and $5.3 as of September 30, 2014 and December 31, 2013, respectively	623.7	528.2
Inventories, net	1,417.70	1,322.10
Prepaid expenses and other current assets	109.4	73.7
Total current assets	2,415	2,950.80
Property, plant and equipment, net	2,937.10	2,874.10
Cost in excess of net assets acquired	782.8	727.9
Other assets	368.3	345.7
Total assets	6,503.20	6,898.50
Current Liabilities:	'	'
Accounts payable	482.7	471.8
Accrued liabilities	305.7	315.8
Deferred income taxes	33.7	3.5
Short-term debt and current portion of long-term debt	17.5	419.9
Total current liabilities	839.6	1,211
Long-term debt	1,509.10	1,527.40
Accrued postretirement benefits	420.5	442.4
Pension liabilities	348.4	368.2
Deferred income taxes	244.6	206.6
Other long-term liabilities	149.3	148.2
Total liabilities	3,511.50	3,903.80
Redeemable noncontrolling interest	12.1	0
ATI Stockholders' Equity:	'	'
Preferred stock, par value $0.10: authorized-50,000,000 shares; issued-none	0	0
Common stock, par value $0.10: authorized-500,000,000 shares; issued-109,695,171 shares at September 30, 2014 and December 31, 2013; outstanding- 108,711,001 shares at September 30, 2014 and 107,983,360 shares at December 31, 2013	11	11
Additional paid-in capital	1,161.90	1,185.90
Retained earnings	2,396.40	2,490.10
Treasury stock: 984,170 shares at September 30, 2014 and 1,711,811 shares at December 31, 2013	-44.5	-79.6
Accumulated other comprehensive loss, net of tax	-653.6	-713.2
Total ATI stockholders’ equity	2,871.20	2,894.20
Noncontrolling interests	'	'
Noncontrolling interests	108.4	100.5
Total Equity	2,979.60	2,994.70
Total Liabilities and Equity	$6,503.20	$6,898.50

CONSOLIDATED_BALANCE_SHEETS_PA

CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowances for doubtful accounts	$4.80	$5.30
Preferred stock, par value	$0.10	$0.10
Preferred stock, authorized	50,000,000	50,000,000
Preferred stock, issued	0	0
Common stock, par value	$0.10	$0.10
Common stock, authorized	500,000,000	500,000,000
Common stock, issued	109,695,171	109,695,171
Common stock, oustanding	108,711,001	107,983,360
Treasury stock	984,170	1,711,811

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]	'	'	'	'
Sales	$1,069.60	$972.40	$3,175.90	$3,128.20
Costs and expenses:	'	'	'	'
Cost of sales	972.6	919.3	2,919.20	2,886.90
Selling and administrative expenses	68.7	70.6	202.1	210.1
Income (loss) before interest, other income and income taxes	28.3	-17.5	54.6	31.2
Interest expense, net	-25.2	-18.2	-82.8	-46.5
Other income, net	1	0.4	2.9	1.3
Income (loss) from continuing operations before income taxes	4.1	-35.3	-25.3	-14
Income tax provision (benefit)	0.5	-8.5	-12.4	-4.4
Income (loss) from continuing operations	3.6	-26.8	-12.9	-9.6
Income (loss) from discontinued operations, net of tax	-0.7	-5.4	-2.8	-4.4
Net income (loss)	2.9	-32.2	-15.7	-14
Less: Net income attributable to noncontrolling interests	3.6	1.6	9	5.4
Net income (loss) attributable to ATI	-0.7	-33.8	-24.7	-19.4
Continuing operations attributable to ATI per common share (in dollars per share)	$0	($0.27)	($0.20)	($0.14)
Discontinued operations attributable to ATI per common share (in dollars per share)	($0.01)	($0.05)	($0.03)	($0.04)
Basic net income (loss) attributable to ATI per common share (in dollars per share)	($0.01)	($0.32)	($0.23)	($0.18)
Continuing operations attributable to ATI per common share (in dollars per share)	$0	($0.27)	($0.20)	($0.14)
Discontinued operations attributable to ATI per common share (in dollars per share)	($0.01)	($0.05)	($0.03)	($0.04)
Diluted net income (loss) attributable to ATI per common share (in dollars per share)	($0.01)	($0.32)	($0.23)	($0.18)
Dividends declared per common share (in dollars per share)	$0.18	$0.18	$0.54	$0.54
Income (loss) from continuing operations, net of tax	0	-28.4	-21.9	-15
Loss from discontinued operations, net of tax	($0.70)	($5.40)	($2.80)	($4.40)

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net loss	$2.90	($32.20)	($15.70)	($14)
Currency translation adjustment	'	'	'	'
Unrealized net change arising during the period	-16.6	12.4	-12.2	3.9
Unrealized holding gain on securities	'	'	'	'
Net gain (loss) arising during the period	0	0.1	0.1	0.1
Derivatives	'	'	'	'
Net derivatives gain (loss) on hedge transactions	28	-18.1	50.1	-21
Reclassification to net income of net realized loss (gain)	-2.6	4.3	-1	5.5
Income taxes on derivative transactions	9.8	-5.3	18.9	-6
Total	15.6	-8.5	30.2	-9.5
Postretirement benefit plans	'	'	'	'
Amortization of net actuarial loss	22.1	33.5	66.1	100.5
Amortization to net income of net prior service credits	-0.2	-3.8	-0.5	-11.4
Income taxes on postretirement benefit plans	8.5	11.4	25.3	34.3
Total	13.4	18.3	40.3	54.8
Other comprehensive income, net of tax	12.4	22.3	58.4	49.3
Comprehensive income (loss)	15.3	-9.9	42.7	35.3
Less: Comprehensive income attributable to noncontrolling interests	5.4	1.7	7.8	7.9
Comprehensive income (loss) attributable to ATI	$9.90	($11.60)	$34.90	$27.40

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating Activities:	'	'
Net loss	($15.70)	($14)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:	'	'
Depreciation and amortization	131.6	143.5
Deferred taxes	15	76.1
Changes in operating asset and liabilities:	'	'
Inventories	-88.6	126.7
Accounts receivable	-89.9	-11.2
Accounts payable	8	-77.4
Retirement benefits	19.3	50.5
Accrued income taxes	-25.1	-82
Accrued liabilities and other	7.2	15.2
Cash provided by (used in) operating activities	-38.2	227.4
Investing Activities:	'	'
Purchases of property, plant and equipment	-157.5	-395.5
Purchases of businesses, net of cash acquired	-92.5	0
Asset disposals and other	1.9	0.8
Cash used in investing activities	-248.1	-394.7
Financing Activities:	'	'
Borrowings on long-term debt	0	500
Payments on long-term debt and capital leases	-414.7	-17
Net borrowings under credit facilities	0	-0.1
Debt issuance costs	0	-5.2
Dividends paid to stockholders	-57.8	-57.7
Dividends paid to noncontrolling interests	0	-18
Taxes on share-based compensation	0	2.6
Exercises of stock options and other	0.1	0.4
Shares repurchased for income tax withholding on share-based compensation	-3.9	-6.6
Cash provided by (used in) financing activities	-476.3	398.4
Increase (decrease) in cash and cash equivalents	'	'
Increase (decrease) in cash and cash equivalents	-762.6	231.1
Cash and cash equivalents at beginning of period	1,026.80	304.6
Cash and cash equivalents at end of period	$264.20	$535.70

STATEMENTS_OF_CHANGES_IN_CONSO

STATEMENTS OF CHANGES IN CONSOLIDATED EQUITY (USD $)	Total	[CommonStockMember]	[AdditionalPaidInCapitalMember]	[RetainedEarningsMember]	[TreasuryStockMember]	[AccumulatedOtherComprehensiveIncomeMember]	[NoncontrollingInterestMember]
In Millions, unless otherwise specified
Total Stockholders' Equity at Dec. 31, 2012	$2,587.10	$11	$1,181.70	$2,427.60	($111.30)	($1,029.40)	$107.50
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'
Net income (loss)	-14	'	'	-19.4	'	'	5.4
Other comprehensive income (loss)	49.3	'	'	'	'	46.8	2.5
Cash dividends on common stock ($0.54 per share)	-57.7	'	'	-57.7	'	'	'
Dividends paid to noncontrolling Interest	-18	'	'	'	'	'	-18
Employee stock plans	17.4	'	-0.5	-14.6	32.5	'	'
Total Stockholders' Equity at Sep. 30, 2013	2,564.10	11	1,181.20	2,335.90	-78.8	-982.6	97.4
Total Stockholders' Equity at Dec. 31, 2013	2,994.70	11	1,185.90	2,490.10	-79.6	-713.2	100.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'
Net income (loss)	-15.7	'	'	-24.7	'	'	'
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Reported in Equity	-15.6	'	'	'	'	'	9.1
Other comprehensive income (loss)	58.4	'	'	'	'	59.6	-1.2
Cash dividends on common stock ($0.54 per share)	-57.8	'	'	-57.8	'	'	'
Conversion of convertible notes	5	'	'	-0.5	5.5	'	'
Employee stock plans	-5.1	'	-24	-10.7	29.6	'	'
Total Stockholders' Equity at Sep. 30, 2014	$2,979.60	$11	$1,161.90	$2,396.40	($44.50)	($653.60)	$108.40

STATEMENTS_OF_CHANGES_IN_CONSO1

STATEMENTS OF CHANGES IN CONSOLIDATED EQUITY (PARENTHETICAL) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Statement of Stockholders' Equity [Abstract]	'	'
Cash dividends on common stock per share	$0.54	$0.54

Accounting_Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2014
Significant Accounting Policies [Abstract]	'
Accounting Policies	'
	Accounting Policies
	The interim consolidated financial statements include the accounts of Allegheny Technologies Incorporated and its subsidiaries. Unless the context requires otherwise, “Allegheny Technologies”, “ATI” and “the Company” refer to Allegheny Technologies Incorporated and its subsidiaries.
	These unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and note disclosures required by U.S. generally accepted accounting principles for complete financial statements. In management’s opinion, all adjustments (which include only normal recurring adjustments) considered necessary for a fair presentation have been included. Certain prior year amounts have been reclassified in order to conform with the fiscal year 2014 presentation. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2013 Annual Report on Form 10-K. The results of operations for these interim periods are not necessarily indicative of the operating results for any future period. The December 31, 2013 financial information has been derived from the Company’s audited consolidated financial statements.
	ATI’s strategic vision is to be an aligned and integrated specialty materials and components company. In connection with this initiative, in the first quarter of 2014, the High Performance Metals segment was renamed the High Performance Materials & Components segment. Individual business unit names within each segment were also changed to reflect their aligned and integrated product focus. There was no change to the business units that comprise each business segment or the manner in which resources are allocated and performance is assessed for the business units by management. Therefore, there was no change to business segment reporting as a result of this initiative.
	New Accounting Pronouncements Adopted
	In January 2014, the Company adopted changes issued by the Financial Accounting Standards Board (FASB) that require an entity to net its liability for unrecognized tax positions against a net operating loss carryforward, a similar tax loss or a tax credit carryforward when settlement in this manner is available under the tax law. The adoption of these changes had no impact on the consolidated financial statements.
	In January 2014, the Company adopted changes issued by the FASB to the accounting for obligations resulting from joint and several liability arrangements. This guidance requires an entity that is joint and severally liable to measure the obligation as the sum of the amount the entity has agreed with co-obligors to pay and any additional amount it expects to pay on behalf of one or more co-obligors. Required disclosures include a description of the nature of the arrangement, how the liability arose, the relationship with co-obligors and the terms and conditions of the arrangement. The adoption of these changes had no impact on the consolidated financial statements.
	In January 2014, the Company adopted changes issued by the FASB to a parent entity’s accounting for the cumulative translation adjustment (CTA) upon derecognition of certain subsidiaries or groups of assets within a foreign entity or of an investment in a foreign entity. The amendments specify that CTA should be released into earnings when an entity ceases to have a controlling financial interest in a subsidiary or group of assets within a consolidated foreign entity and the sale or transfer results in the complete or substantially complete liquidation of the foreign entity. For sales of an equity method investment that is a foreign entity, a pro rata portion of CTA attributable to the investment would be recognized in earnings when the investment is sold. When an entity sells either a part or all of its investment in a consolidated foreign entity, CTA would be recognized in earnings only if the sale results in the parent no longer having a controlling financial interest in the foreign entity. In addition, CTA should be recognized in earnings in a business combination achieved in stages (i.e., a step acquisition). The adoption of these changes had no impact on the consolidated financial statements.
	Pending Accounting Pronouncements
	In May 2014, the FASB issued changes to revenue recognition with customers. This update provides a five-step analysis of transactions to determine when and how revenue is recognized. An entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update will be effective for the Company beginning in fiscal year 2017. This update may be applied retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying this update recognized at the date of initial application. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements.
	In April 2014, the FASB issued changes to the criteria for reporting discontinued operations. Under the new criteria, a disposal of a component of an entity is required to be reported as discontinued operations only if the disposal represents a strategic shift that has, or will have, a major effect on an entity’s operations and financial results. The current criteria that there be no significant continuing involvement in the operations of the component after the disposal transaction has been removed under the new guidance. The new guidance also requires the presentation of the assets and liabilities of a disposal group that includes a discontinued operation for each comparative period and requires additional disclosures about discontinued operations, including the major line items constituting the pretax profit or loss of the discontinued operation, certain cash flow information for the discontinued operation, expanded disclosures about an entity’s significant continuing involvement in a discontinued operation, and disclosures about a disposal of an individually significant component of an entity that does not qualify for discontinued operations presentation. The provisions of the new guidance become effective for all disposals that occur for the Company beginning in fiscal year 2015. The Company does not anticipate a material impact to the consolidated financial statements upon adoption.

Acquisition_of_Business_Acquis

Acquisition of Business Acquisition of Business	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Acquisition of Business	'
	Acquisition of Business
	On February 7, 2014, the Company acquired 85% of Dynamic Flowform Corp. (“Dynamic Flowform”) for $72.9 million of cash consideration, net of cash acquired. The Dynamic Flowform acquisition is treated as an asset purchase for tax purposes. The holders of the 15% noncontrolling interest have a put option requiring the Company to purchase their equity interest (see Note 12 for additional explanation). The Company also incurred $0.7 million of pre-tax costs related to the acquisition, consisting primarily of professional fees, which were recorded in selling and administrative expenses in the nine months ended September 30, 2014 consolidated statement of operations.
	Based in Billerica, MA, Dynamic Flowform, which has been renamed ATI Flowform Products, uses precision flowforming process technologies to produce thin-walled components in net or near-net shapes across multiple alloy systems, including nickel-based alloys and superalloys, titanium and titanium alloys, zirconium alloys, and specialty and stainless alloys. Management expects this acquisition to expand the Company’s capabilities to produce specialty materials parts and components, primarily in the aerospace and defense, and oil & gas/chemical process industry markets. ATI Flowform Products results are included in the High Performance Materials & Components segment from the date of the acquisition.
	The purchase price allocation includes technology, trademarks and customer intangible assets of $21.4 million, which will be amortized over a 23 year weighted average life, and goodwill of $46.8 million, which is deductible for tax purposes. The final allocation of the purchase price was completed in the second quarter of 2014.
	In addition, on June 12, 2014, the Company acquired Hanard Machine, Inc. (“Hanard”) for $20.5 million of cash consideration, net of cash acquired, including $19.6 million paid in the first nine months of 2014 and $0.9 million that is expected to be paid within the next twelve months. Located in Salem, OR, Hanard performs precision machining on parts and components made from titanium alloys, nickel-based alloys and superalloys, aluminum, specialty steel, and other ferrous and non-ferrous metals. The business operates as ATI Cast Products, Salem Operations, and is reported as a part of the High Performance Materials & Components segment from the date of the acquisition. Management expects this acquisition to expand the Company’s capabilities to produce finished specialty materials parts and components and reinforces the Company’s important aerospace supply chain role.  The purchase price allocation includes technology and customer intangible assets of $4.3 million, which will be amortized over a 20 year life, and goodwill of $8.3 million, which is deductible for tax purposes. The final allocation of the purchase price is expected to be completed by the end of the fourth quarter of 2014.
	Pro forma financial information has not been included because these acquisitions did not meet certain significance thresholds individually or in the aggregate.

Discontinued_Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Discontinued Operations	'
	Discontinued Operations
	On November 4, 2013, the Company completed the sale of its tungsten materials business, which produced tungsten powder, tungsten heavy alloys, tungsten carbide materials, and carbide cutting tools. The operating results for this business have been included in discontinued operations in the Company’s consolidated statement of operations for the three and nine months ended September 30, 2013.
	Also, during the third quarter of 2013, the Company completed a strategic review of its iron castings and fabricated components businesses. Based on the then-current and forecasted results, these businesses were not projected to meet the Company’s long-term profitable growth and return on capital employed expectations resulting in the closure of the fabricated components business and planned divestiture of the iron casting business in 2013. In April 2014, the Company announced plans to close its iron castings business, as the divestiture of this business through a sale process on commercially acceptable terms was unlikely to be successful. The orderly wind-down of operations was completed by the end of the third quarter 2014 and resulted in $1.7 million of cash exit costs in 2014, primarily related to severance benefits, of which $0.5 million was recorded in the third quarter and $1.2 million was recorded in the second quarter as part of the results of discontinued operations. Payment of cash exit costs is expected to be completed within the next twelve months. Results of discontinued operations for the third quarter of 2013 include $9.5 million pre-tax ($8.1 million after-tax) of charges, primarily non-cash asset impairment charges, associated with the iron castings and fabricated components divestitures. The operating results of these businesses have been included in discontinued operations in the Company’s consolidated statements of operations for all periods presented.
	The following table presents summarized operating results for these discontinued operations (in millions):
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Sales	$	3.3		$	77.6		$	14.9		$	236.7
	Loss before income tax benefit	$	(0.5	)	$	(7.1	)	$	(3.5	)	$	(5.4	)

Inventories

Inventories	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories at September 30, 2014 and December 31, 2013 were as follows (in millions):
		September 30,			December 31,
		2014			2013
	Raw materials and supplies	$	262.1		$	277.6
	Work-in-process	1,130.70			984.9
	Finished goods	165.5			162.1
	Total inventories at current cost	1,558.30			1,424.60
	Adjustment from current cost to LIFO cost basis	(18.5		)	29.4
	Inventory valuation reserves	(54.5		)	(84.3		)
	Progress payments	(67.6		)	(47.6		)
	Total inventories, net	$	1,417.70		$	1,322.10
	Inventories are stated at the lower of cost (last-in, first-out (“LIFO”), first-in, first-out (“FIFO”), and average cost methods) or market, less progress payments. Most of the Company’s inventory is valued utilizing the LIFO costing methodology. Inventory of the Company’s non-U.S. operations is valued using average cost or FIFO methods. The effect of using the LIFO methodology to value inventory, rather than FIFO, increased cost of sales by $47.9 million for the first nine months of 2014, which was offset by a $35.0 million reduction in net realizable value reserves on the carrying value of LIFO-based inventory. The first nine months of 2013 results included a $39.1 million decrease in cost of sales from using the LIFO costing methodology. The first nine months of 2014 results included $18.3 million in inventory valuation charges related to the market-based valuation of industrial titanium products in the Flat Rolled Products segment.

Property_Plant_And_Equipment

Property Plant And Equipment	9 Months Ended
	Sep. 30, 2014
Property, Plant and Equipment [Abstract]	'
Property Plant and Equipment	'
	Property, Plant and Equipment
	Property, plant and equipment at September 30, 2014 and December 31, 2013 was as follows (in millions):
		September 30,			December 31,
		2014			2013
	Land	$	30		$	30.2
	Buildings	1,035.40			1,019.10
	Equipment and leasehold improvements	3,668.90			3,526.00
		4,734.30			4,575.30
	Accumulated depreciation and amortization	(1,797.2		)	(1,701.2		)
	Total property, plant and equipment, net	$	2,937.10		$	2,874.10
	The construction in progress portion of property, plant and equipment at September 30, 2014 was $84.1 million.

Debt

Debt	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	Debt at September 30, 2014 and December 31, 2013 was as follows (in millions):
		September 30,		December 31,
		2014		2013
	Allegheny Technologies 5.875% Notes due 2023	$	500	$	500
	Allegheny Technologies 5.95% Notes due 2021	500		500
	Allegheny Technologies 4.25% Convertible Notes due 2014	—		402.5
	Allegheny Technologies 9.375% Notes due 2019	350		350
	Allegheny Ludlum 6.95% debentures due 2025	150		150
	ATI Ladish Series B 6.14% Notes due 2016 (a)	12		18.2
	ATI Ladish Series C 6.41% Notes due 2015 (b)	10.4		21.1
	Domestic Bank Group $400 million unsecured credit facility	—		—
	Foreign credit facilities	—		—
	Industrial revenue bonds, due through 2020, and other	4.2		5.5
	Total short-term and long-term debt	1,526.60		1,947.30
	Short-term debt and current portion of long-term debt	17.5		419.9
	Total long-term debt	$	1,509.10	$	1,527.40
	(a)	Includes fair value adjustments of $0.6 million at September 30, 2014 and $1.0 million at December 31, 2013.
	(b)	Includes fair value adjustments of $0.4 million at September 30, 2014 and $1.1 million at December 31, 2013.
	On June 2, 2014, the Company repaid the remaining $397.5 million outstanding of the 4.25% Convertible Senior Notes (Convertible Notes). Holders of the Convertible Notes had the option to convert their notes into shares of ATI common stock at any time prior to the close of business on the second scheduled trading day immediately preceding the June 1, 2014 maturity date. Prior to the maturity date, $5.0 million of the Convertible Notes were converted into 120,476 shares of ATI common stock. The conversion rate for the Convertible Notes was 23.9263 shares of ATI common stock per $1,000 principal amount of Convertible Notes, equivalent to a conversion price of approximately $41.795 per share. Other than receiving cash in lieu of fractional shares, holders did not have the option to receive cash instead of shares of common stock upon conversion.
	There were no outstanding borrowings made under the Company’s $400 million senior unsecured domestic credit facility ("credit facility") expiring May 31, 2018 as of September 30, 2014, although approximately $5.1 million has been utilized to support the issuance of letters of credit. The credit facility requires the Company to maintain a leverage ratio (consolidated total indebtedness net of cash on hand in excess of $50 million, divided by consolidated earnings before interest, taxes, depreciation and amortization, and non-cash pension expense for the four prior fiscal quarters) of not greater than 4.0. The credit facility also requires the Company to maintain an interest coverage ratio (consolidated earnings before interest, taxes and non-cash pension expense divided by interest expense) of not less than 2.0. At September 30, 2014, the leverage ratio was 2.13 and the interest coverage ratio was 4.62. The Company was in compliance with these required ratios during all applicable periods.
	In October 2014, the Company amended the credit facility to modify the maximum leverage ratio and minimum interest coverage ratio permitted under the credit facility and to revise the calculation definitions for these two ratios. In addition, the Company amended the credit facility to provide for a springing lien on certain of the Company’s accounts receivable and inventory. This springing lien would become effective in the future if the Company’s credit ratings from both Standard & Poor’s and Moody’s are below investment grade, and would be subsequently released if the Company’s credit rating returns to investment grade from either rating agency, assuming no event of default condition existed. As amended, the credit facility requires the Company to maintain a leverage ratio (measured as consolidated total indebtedness net of cash on hand in excess of $50 million, divided by consolidated EBITDA, defined as earnings before interest, taxes, depreciation and amortization, and non-cash pension expense, with the definition of consolidated EBIT excluding any gain or loss attributable to sale or other dispositions of assets outside the ordinary course of business, for the four prior fiscal quarters) of not greater than 5.75 for the quarter ended December 31, 2014, 5.00 for the quarter ended March 31, 2015, 4.50 for the quarter ended June 30, 2015, 3.75 for the quarter ended September 30, 2015, and 3.50 for the quarter ended December 31, 2015 and for each fiscal quarter thereafter. The credit facility, as amended, also requires the Company to maintain an interest coverage ratio (consolidated EBITDA as calculated for the leverage ratio, divided by interest expense) of not less than 2.0 for the quarter ended December 31, 2014, 2.50 for the quarter ended March 31, 2015, 3.00 for the quarter ended June 30, 2015, 3.25 for the quarter ended September 30, 2015, and 3.50 for the quarter ended December 31, 2015 and for each fiscal quarter thereafter.
	The Company has an additional separate credit facility for the issuance of letters of credit. As of September 30, 2014, $32 million in letters of credit were outstanding under this facility.
	In addition, Shanghai STAL Precision Stainless Steel Company Limited (STAL), the Company’s Chinese joint venture company in which ATI has a 60% interest, had a 205 million renminbi (approximately $33 million at September 30, 2014 exchange rates) revolving credit facility with a group of banks, which expired on August 8, 2014. Replacement of the credit facility is currently under management review.
	The ATI Ladish Series B and Series C Notes are guaranteed by ATI and are equally ranked with all of ATI’s existing and future senior unsecured debt.

Derivative_Financial_Instrumen

Derivative Financial Instruments and Hedging	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Financial Instruments and Hedging	'
	Derivative Financial Instruments and Hedging
	As part of its risk management strategy, the Company, from time-to-time, utilizes derivative financial instruments to manage its exposure to changes in raw material prices, energy costs, foreign currencies, and interest rates. In accordance with applicable accounting standards, the Company accounts for most of these contracts as hedges. In general, hedge effectiveness is determined by examining the relationship between offsetting changes in fair value or cash flows attributable to the item being hedged, and the financial instrument being used for the hedge. Effectiveness is measured utilizing regression analysis and other techniques to determine whether the change in the fair market value or cash flows of the derivative exceeds the change in fair value or cash flow of the hedged item. Calculated ineffectiveness, if any, is immediately recognized in the consolidated statements of operations.
	The Company sometimes uses futures and swap contracts to manage exposure to changes in prices for forecasted purchases of raw materials, such as nickel and natural gas. Under these contracts, which are generally accounted for as cash flow hedges, the price of the item being hedged is fixed at the time that the contract is entered into and the Company is obligated to make or receive a payment equal to the net change between this fixed price and the market price at the date the contract matures.
	The majority of ATI’s products are sold utilizing raw material surcharges and index mechanisms. However, as of September 30, 2014, the Company had entered into financial hedging arrangements primarily at the request of its customers, related to firm orders, for an aggregate notional amount of approximately 15% of its estimated annual nickel requirements. These nickel hedges extend to 2020.
	At September 30, 2014, the outstanding financial derivatives used to hedge the Company’s exposure to energy cost volatility included natural gas cost hedges for approximately 80% of its annual forecasted domestic requirements for 2014, approximately 85% for 2015, approximately 65% for 2016, and approximately 20% for 2017, and electricity hedges for Western Pennsylvania operations of approximately 10% of its forecasted on-peak and off-peak requirements for 2014.
	While the majority of the Company’s direct export sales are transacted in U.S. dollars, foreign currency exchange contracts are used, from time-to-time, to limit transactional exposure to changes in currency exchange rates for those transactions denominated in a non-U.S. currency. The Company sometimes purchases foreign currency forward contracts that permit it to sell specified amounts of foreign currencies expected to be received from its export sales for pre-established U.S. dollar amounts at specified dates. The forward contracts are denominated in the same foreign currencies in which export sales are denominated. These contracts are designated as hedges of the variability in cash flows of a portion of the forecasted future export sales transactions which otherwise would expose the Company to foreign currency risk. The Company may also enter into foreign currency forward contracts that are not designated as hedges, which are denominated in the same foreign currency in which export sales are denominated. At September 30, 2014, the outstanding financial derivatives, including both hedges and undesignated derivatives, that are used to manage the Company’s exposure to foreign currency, primarily euros, represented approximately 20% of its forecasted total international sales through 2018. In addition, the Company may also designate cash balances held in foreign currencies as hedges of forecasted foreign currency transactions.
	The Company may enter into derivative interest rate contracts to maintain a reasonable balance between fixed- and floating-rate debt. There were no unsettled derivative financial instruments related to debt balances for the periods presented.
	There are no credit risk-related contingent features in the Company’s derivative contracts, and the contracts contained no provisions under which the Company has posted, or would be required to post, collateral. The counterparties to the Company’s derivative contracts are substantial and creditworthy commercial banks that are recognized market makers. The Company controls its credit exposure by diversifying across multiple counterparties and by monitoring credit ratings and credit default swap spreads of its counterparties. The Company also enters into master netting agreements with counterparties when possible.
	The fair values of the Company’s derivative financial instruments are presented below, representing the gross amounts recognized which are not offset by counterparty or by type of item hedged. All fair values for these derivatives were measured using Level 2 information as defined by the accounting standard hierarchy, which includes quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs derived principally from or corroborated by observable market data.
	(In millions)		Balance sheet location		September 30,				December 31,
	Asset derivatives				2014				2013
	Derivatives designated as hedging instruments:
	Foreign exchange contracts		Prepaid expenses and other current assets		$	14			$	0.3
	Nickel and other raw material contracts		Prepaid expenses and other current assets		3.3				0.1
	Natural gas contracts		Prepaid expenses and other current assets		0.3				2.5
	Foreign exchange contracts		Other assets		20.5				—
	Nickel and other raw material contracts		Other assets		2.4				0.4
	Natural gas contracts		Other assets		0.4				1
	Total derivatives designated as hedging instruments				40.9				4.3
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts		Prepaid expenses and other current assets		4.8				—
	Total derivatives not designated as hedging instruments				4.8				—
	Total asset derivatives				$	45.7			$	4.3
	Liability derivatives		Balance sheet location
	Derivatives designated as hedging instruments:
	Natural gas contracts		Accrued liabilities		$	2.1			$	0.4
	Nickel and other raw material contracts		Accrued liabilities		2.1				4.5
	Foreign exchange contracts		Accrued liabilities		—				7.8
	Electricity contracts		Accrued liabilities		0.1				0.5
	Natural gas contracts		Other long-term liabilities		2.1				—
	Foreign exchange contracts		Other long-term liabilities		—				5.4
	Nickel and other raw material contracts		Other long-term liabilities		1				1.3
	Total derivatives designated as hedging instruments				7.4				19.9
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts		Accrued liabilities		—				1.7
	Total derivatives not designated as hedging instruments				—				1.7
	Total liability derivatives				$	7.4			$	21.6
	For derivative financial instruments that are designated as cash flow hedges, the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive income (OCI) and reclassified into earnings in the same period or periods during which the hedged item affects earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current period results. The Company did not use fair value or net investment hedges for the periods presented. The effects of derivative instruments in the tables below are presented net of related income taxes.
	Activity with regard to derivatives designated as cash flow hedges for the three and nine month periods ended September 30, 2014 and 2013 was as follows (in millions):
		Amount of Gain (Loss)								Amount of Gain (Loss)						Amount of Gain (Loss)
		Recognized in OCI on								Reclassified from						Recognized in Income
		Derivatives								Accumulated OCI						on Derivatives (Ineffective
		(Effective Portion)								into Income						Portion and Amount
										(Effective Portion) (a)						Excluded from
																Effectiveness Testing) (b)
	Derivatives in Cash Flow	Three months ended September 30,								Three months ended September 30,						Three months ended September 30,
	Hedging Relationships	2014				2013				2014			2013			2014		2013
	Nickel and other raw material contracts	$	(4.7	)		$	0.2			$	1.3		$	(1.3	)	$	—	$	—
	Natural gas contracts	(3.0		)		0.1				—			(0.6		)	—		—
	Electricity contracts	(0.2		)		(0.1		)		(0.1		)	—			—		—
	Foreign exchange contracts	25.1				(11.3		)		0.4			(0.7		)	—		—
	Total	$	17.2			$	(11.1	)		$	1.6		$	(2.6	)	$	—	$	—
		Amount of Gain (Loss)								Amount of Gain (Loss)						Amount of Gain (Loss)
		Recognized in OCI on								Reclassified from						Recognized in Income
		Derivatives								Accumulated OCI						on Derivatives (Ineffective
		(Effective Portion)								into Income						Portion and Amount
										(Effective Portion) (a)						Excluded from
																Effectiveness Testing) (b)
	Derivatives in Cash Flow	Nine months ended September 30,								Nine months ended September 30,						Nine months ended September 30,
	Hedging Relationships	2014				2013				2014			2013			2014		2013
	Nickel and other raw material contracts	$	5.4			$	(8.6	)		$	0.5		$	(2.3	)	$	—	$	—
	Natural gas contracts	(1.7		)		(0.2		)		2.4			(1.5		)	—		—
	Electricity contracts	0.6				(0.1		)		0.4			(0.2		)	—		—
Foreign exchange contracts	26.5				(4.0		)		(2.7		)	0.6			—		—
Total	$	30.8			$	(12.9	)		$	0.6		$	(3.4	)	$	—	$	—
(a)	The gains (losses) reclassified from accumulated OCI into income related to the effective portion of the derivatives are presented in cost of sales in the same period or periods in which the hedged item affects earnings.
(b)	The gains (losses) recognized in income on derivatives related to the ineffective portion and the amount excluded from effectiveness testing are presented in selling and administrative expenses.
Assuming market prices remain constant with those at September 30, 2014, a gain of $8.3 million is expected to be recognized over the next 12 months.
The disclosures of gains or losses presented above for nickel and other raw material contracts and foreign currency contracts do not take into account the anticipated underlying transactions. Since these derivative contracts represent hedges, the net effect of any gain or loss on results of operations may be fully or partially offset.
Derivatives that are not designated as hedging instruments were as follows:
(In millions)	Amount of Gain (Loss) Recognized
	in Income on Derivatives
Derivatives Not Designated	Three months ended September 30,								Nine months ended September 30,
as Hedging Instruments	2014				2013				2014			2013
Foreign exchange contracts	$	3.1			$	(0.7	)		$	4.2		$	(0.3	)
Changes in the fair value of foreign exchange contract derivatives not designated as hedging instruments are recorded in cost of sales.

Fair_Value_Of_Financial_Instru

Fair Value Of Financial Instruments	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Of Financial Instruments	'
	Fair Value of Financial Instruments
	The estimated fair value of financial instruments at September 30, 2014 was as follows:
				Fair Value Measurements at Reporting Date Using
	(In millions)	Total		Total		Quoted Prices in		Significant
		Carrying		Estimated		Active Markets for		Observable
		Amount		Fair Value		Identical Assets(Level 1)		Inputs
								(Level 2)
	Cash and cash equivalents	$	264.2	$	264.2	$	264.2	$	—
	Derivative financial instruments:
	Assets	45.7		45.7		—		45.7
	Liabilities	7.4		7.4		—		7.4
	Debt	1,526.60		1,700.10		1,673.50		26.6
	The estimated fair value of financial instruments at December 31, 2013 was as follows:
				Fair Value Measurements at Reporting Date Using
	(In millions)	Total		Total		Quoted Prices in		Significant
		Carrying		Estimated		Active Markets for		Observable
		Amount		Fair Value		Identical Assets		Inputs
						(Level 1)		(Level 2)
	Cash and cash equivalents	$	1,026.80	$	1,026.80	$	1,026.80	$	—
	Derivative financial instruments:
	Assets	4.3		4.3		—		4.3
	Liabilities	21.6		21.6		—		21.6
	Debt	1,947.30		2,072.60		2,027.80		44.8
	In accordance with accounting standards, fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Accounting standards established three levels of a fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows:
	Level 1 – Quoted prices in active markets for identical assets or liabilities.
	Level 2 – Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.
	Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.
	The following methods and assumptions were used by the Company in estimating the fair value of its financial instruments:
	Cash and cash equivalents: Fair value was determined using Level 1 information.
	Derivative financial instruments: Fair values for derivatives were measured using exchange-traded prices for the hedged items. The fair value was determined using Level 2 information, including consideration of counterparty risk and the Company’s credit risk.
	Short-term and long-term debt: The fair values of the Company’s publicly traded debt were based on Level 1 information. The fair values of the other short-term and long-term debt were determined using Level 2 information.

Pension_Plans_and_Other_Postre

Pension Plans and Other Postretirement Benefits	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Pension Plans and Other Postretirement Benefits	'
	Pension Plans and Other Postretirement Benefits
	The Company has defined benefit pension plans and defined contribution plans covering substantially all employees. Benefits under the defined benefit pension plans are generally based on years of service and/or final average pay. The Company funds the U.S. pension plans in accordance with the Employee Retirement Income Security Act of 1974, as amended, and the Internal Revenue Code.
	The Company also sponsors several postretirement plans covering certain salaried and hourly employees. The plans provide health care and life insurance benefits for eligible retirees. In most plans, Company contributions towards premiums are capped based on the cost as of a certain date, thereby creating a defined contribution. For the non-collectively bargained plans, the Company maintains the right to amend or terminate the plans at its discretion.
	For the three month periods ended September 30, 2014 and 2013, the components of pension expense and components of other postretirement benefit expense for the Company’s defined benefit plans included the following (in millions):
		Pension Benefits						Other Postretirement Benefits
		Three months ended September 30,						Three months ended September 30,
		2014			2013			2014			2013
	Service cost - benefits earned during the year	$	7.3		$	10		$	0.7		$	0.8
	Interest cost on benefits earned in prior years	33.4			30.3			6			5.6
	Expected return on plan assets	(46.1		)	(43.8		)	(0.1		)	(0.1		)
	Amortization of prior service cost (credit)	0.6			0.8			(0.8		)	(4.6		)
	Amortization of net actuarial loss	18.5			29.2			3.6			4.3
	Termination benefits	—			—			—			—
	Total retirement benefit expense	$	13.7		$	26.5		$	9.4		$	6
	For the nine month periods ended September 30, 2014 and 2013, the components of pension expense and components of other postretirement benefit expense for the Company’s defined benefit plans included the following (in millions):
		Pension Benefits						Other Postretirement Benefits
		Nine months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost - benefits earned during the year	$	22		$	30		$	2.1		$	2.4
	Interest cost on benefits earned in prior years	100.2			90.9			18			16.8
	Expected return on plan assets	(138.2		)	(131.4		)	(0.2		)	(0.3		)
	Amortization of prior service cost (credit)	1.8			2.3			(2.3		)	(13.7		)
	Amortization of net actuarial loss	55.5			87.6			10.6			12.9
	Termination benefits	0.3			—			—			—
	Total retirement benefit expense	$	41.6		$	79.4		$	28.2		$	18.1
	Other postretirement benefit costs for a defined contribution plan were $0.7 million and $2.0 million for the three months ended September 30, 2014 and 2013, respectively and $2.0 million for both nine month periods ended September 30, 2014 and 2013.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	Third quarter 2014 results included a provision for income taxes of $0.5 million, or 12.2% of income from continuing operations before income tax, compared to a benefit of $8.5 million, or 24.1% of loss from continuing operations before income tax, for the 2013 comparable period. Income taxes in the third quarter 2014 and 2013 included discrete tax benefits of $3.4 million and $2.1 million, respectively, primarily associated with adjustments to prior years’ and foreign taxes.
	For the first nine months of 2014, the benefit for income taxes was $12.4 million, or 49.0% of loss from continuing operations before income tax, compared to a benefit of $4.4 million, or 31.4% of loss from continuing operations before income tax, for the comparable 2013 period. The first nine months of 2014 included a discrete tax benefit of $7.8 million, primarily associated with adjustments to prior years’ and foreign taxes. Excluding the discrete tax benefits, the effective tax rate for the first nine months of 2014 was 18.4%. The first nine months of 2013 included a discrete tax benefit of $6.7 million, primarily associated with adjustments to prior years’ taxes and 2013 Federal tax law changes.

Business_Segments

Business Segments	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Business Segments	'
	Business Segments
	The Company operates in two business segments: High Performance Materials & Components and Flat Rolled Products. Our measure of segment operating profit, which is used to analyze the performance and results of the business segments, excludes income taxes, corporate expenses, net interest expense, retirement benefit expense, closed company expenses and restructuring costs, if any. Discontinued operations are also excluded. Management believes segment operating profit, as defined, provides an appropriate measure of controllable operating results at the business segment level. Following is certain financial information with respect to the Company’s business segments for the periods indicated (in millions):
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Total sales:
	High Performance Materials & Components	$	527.1		$	481.2		$	1,562.60		$	1,561.70
	Flat Rolled Products	587			515.6			1,747.10			1,644.00
		1,114.10			996.8			3,309.70			3,205.70
	Intersegment sales:
	High Performance Materials & Components	19.4			17.3			56.4			53.6
	Flat Rolled Products	25.1			7.1			77.4			23.9
		44.5			24.4			133.8			77.5
	Sales to external customers:
	High Performance Materials & Components	507.7			463.9			1,506.20			1,508.10
	Flat Rolled Products	561.9			508.5			1,669.70			1,620.10
		$	1,069.60		$	972.4		$	3,175.90		$	3,128.20
	Operating profit (loss):
	High Performance Materials & Components	$	62		$	48		$	216.2		$	192
	Flat Rolled Products	8.6			(20.4		)	(36.9		)	(16.7		)
	Total operating profit	70.6			27.6			179.3			175.3
	Corporate expenses	(10.0		)	(8.1		)	(33.2		)	(32.3		)
	Interest expense, net	(25.2		)	(18.2		)	(82.8		)	(46.5		)
	Closed company and other expenses	(7.5		)	(2.1		)	(16.8		)	(11.0		)
	Retirement benefit expense	(23.8		)	(34.5		)	(71.8		)	(99.5		)
	Income (loss) from continuing operations before income taxes	$	4.1		$	(35.3	)	$	(25.3	)	$	(14.0	)
	Retirement benefit expense represents defined benefit plan pension expense and other postretirement benefit expense for both defined benefit and defined contribution plans. Operating profit with respect to the Company’s business segments excludes any retirement benefit expense. Costs associated with multiemployer pension plans are included in segment operating profit, and costs associated with defined contribution pension plans are included in segment operating profit or corporate expenses, as applicable.
	Interest expense, net of interest income, in the third quarter 2014 was $25.2 million, compared to net interest expense of $18.2 million in the third quarter 2013. The increase in interest expense was primarily due to reduced capitalized interest, partially offset by lower debt levels following the maturity of the $402.5 million convertible notes in June 2014. Interest expense benefited from the capitalization of interest costs of $0.9 million in the third quarter 2014 compared to $12.7 million in the third quarter 2013. The decrease in capitalized interest is due to a lower construction in progress balance, primarily related to the Flat Rolled Products segment Hot-Rolling and Processing Facility.
	Closed company and other expenses primarily includes charges incurred in connection with closed operations and other non-operating income or expense. These items are presented primarily in selling and administrative expenses and in other income in the statements of operations. These items resulted in net charges of $7.5 million for the three months ended September 30, 2014 and $2.1 million for the three months ended September 30, 2013 largely due to an increase in environmental expenses and insurance costs associated with closed operations.

Redeemable_Noncontrolling_Inte

Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interest [Abstract]	'
Redeemable Noncontrolling Interest	'
	Redeemable Noncontrolling Interest
	The holders of the 15% noncontrolling interest in ATI Flowform Products have a put option to require the Company to purchase their equity interest at a redemption value determinable from a specified formula based on a multiple of EBITDA (subject to a fixed minimum linked to the original acquisition date value). The put option is fully exercisable beginning in the second quarter of 2017, and is also exercisable under certain other circumstances. The put option cannot be separated from the noncontrolling interest, and the combination of a noncontrolling interest and the redemption feature requires classification as redeemable noncontrolling interest in the consolidated balance sheet, separate from Stockholders’ Equity.
	The carrying amount of the redeemable noncontrolling interest approximates its maximum redemption value. Any subsequent change in maximum redemption value is adjusted through retained earnings. The redeemable noncontrolling interest was $12.1 million as of September 30, 2014, which was unchanged from the acquisition date value.

Per_Share_Information

Per Share Information	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Per Share Information	'
	Per Share Information
	The following table sets forth the computation of basic and diluted income from continuing operations per common share:
		Three Months Ended					Nine months ended
	(In millions, except per share amounts)	September 30,					September 30,
		2014		2013			2014			2013
	Numerator for basic income (loss) from continuing operations per common share –
	Income (loss) from continuing operations attributable to ATI	$	—	$	(28.4	)	$	(21.9	)	$	(15.0	)
	Effect of dilutive securities:
	4.25% Convertible Notes due 2014	—		—			—			—
	Numerator for diluted income (loss) from continuing operations per common share –
	Income (loss) from continuing operations available to ATI after assumed conversions	$	—	$	(28.4	)	$	(21.9	)	$	(15.0	)
	Denominator for basic net income (loss) per common share-weighted average shares	107.2		106.8			107.1			106.7
	Effect of dilutive securities:
	Share-based compensation	0.8		—			—			—
	4.25% Convertible Notes due 2014	—		—			—			—
	Denominator for diluted net income (loss) per common share – adjusted weighted average shares assuming conversions	108		106.8			107.1			106.7
	Basic income (loss) from continuing operations attributable to ATI per common share	$	—	$	(0.27	)	$	(0.20	)	$	(0.14	)
	Diluted income (loss) from continuing operations attributable to ATI per common share	$	—	$	(0.27	)	$	(0.20	)	$	(0.14	)
	Common stock that would be issuable upon the assumed conversion of the 2014 Convertible Notes (prior to maturity on June 2, 2014) and other option equivalents and contingently issuable shares are excluded from the computation of contingently issuable shares, and therefore, from the denominator for diluted earnings per share, if the effect of inclusion is anti-dilutive. There were 6.0 million anti-dilutive shares for the nine month period ended September 30, 2014, and 10.0 million anti-dilutive shares for the three and nine month periods ended September 30, 2013. There were no anti-dilutive shares for the three months ended September 30, 2014.

Financial_Information_for_Subs

Financial Information for Subsidiary and Guarantor Parent	9 Months Ended
	Sep. 30, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Financial Information for Subsidiary and Guarantor Parent	'
	Financial Information for Subsidiary and Guarantor Parent
	The payment obligations under the $150 million 6.95% debentures due 2025 issued by Allegheny Ludlum, LLC (the “Subsidiary”) are fully and unconditionally guaranteed by Allegheny Technologies Incorporated (the “Guarantor Parent”). In accordance with positions established by the Securities and Exchange Commission, the following financial information sets forth separately financial information with respect to the Subsidiary, the Non-guarantor Subsidiaries and the Guarantor Parent. The principal elimination entries eliminate investments in subsidiaries and certain intercompany balances and transactions.
	ATI is the plan sponsor for the U.S. qualified defined benefit pension plan (the “Plan”) which covers certain current and former employees of the Subsidiary and the Non-guarantor Subsidiaries. As a result, the balance sheets presented for the Subsidiary and the Non-guarantor Subsidiaries do not include any Plan assets or liabilities, or the related deferred taxes. The Plan assets, liabilities and related deferred taxes and pension income or expense are recognized by the Guarantor Parent. Management and royalty fees charged to the Subsidiary and to the Non-guarantor Subsidiaries by the Guarantor Parent have been excluded solely for purposes of this presentation.
	Allegheny Technologies Incorporated
	Financial Information for Subsidiary and Guarantor Parent
	Balance Sheets
	September 30, 2014
	(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
		Parent						Subsidiaries
	Assets:
	Cash and cash equivalents	$	6		$	18.1		$	240.1		$	—		$	264.2
	Accounts receivable, net	0.4			229.5			393.8			—			623.7
	Intercompany notes receivable	—			—			2,534.30			(2,534.3		)	—
	Inventories, net	—			356.8			1,060.90			—			1,417.70
	Prepaid expenses and other current assets	51.8			12.5			45.1			—			109.4
	Total current assets	58.2			616.9			4,274.20			(2,534.3		)	2,415.00
	Property, plant and equipment, net	2.3			1,502.90			1,431.90			—			2,937.10
	Cost in excess of net assets acquired	—			126.6			656.2			—			782.8
	Intercompany notes receivable	—			—			200			(200.0		)	—
	Investment in subsidiaries	6,404.80			37.7			—			(6,442.5		)	—
	Other assets	25.3			28.1			314.9			—			368.3
	Total assets	$	6,490.60		$	2,312.20		$	6,877.20		$	(9,176.8	)	$	6,503.20
	Liabilities and stockholders’ equity:
	Accounts payable	$	5.5		$	299.9		$	177.3		$	—		$	482.7
	Accrued liabilities	38			65.5			202.2			—			305.7
	Intercompany notes payable	1,454.70			1,079.60			—			(2,534.3		)	—
	Deferred income taxes	33.7			—			—			—			33.7
	Short-term debt and current portion of long-term debt	0.5			0.1			16.9			—			17.5
	Total current liabilities	1,532.40			1,445.10			396.4			(2,534.3		)	839.6
	Long-term debt	1,350.70			150.3			8.1			—			1,509.10
	Intercompany notes payable	—			200			—			(200.0		)	—
	Accrued postretirement benefits	—			174.1			246.4			—			420.5
	Pension liabilities	304.2			5.2			39			—			348.4
	Deferred income taxes	244.6			—			—			—			244.6
	Other long-term liabilities	79.1			21.2			49			—			149.3
	Total liabilities	3,511.00			1,995.90			738.9			(2,734.3		)	3,511.50
	Redeemable noncontrolling interest	—			—			12.1			—			12.1
	Total stockholders’ equity	2,979.60			316.3			6,126.20			(6,442.5		)	2,979.60
	Total liabilities and stockholders’ equity	$	6,490.60		$	2,312.20		$	6,877.20		$	(9,176.8	)	$	6,503.20
	Allegheny Technologies Incorporated
	Financial Information for Subsidiary and Guarantor Parent
	Statements of Operations and Comprehensive Income
	For the three months ended September 30, 2014
	(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
		Parent						Subsidiaries
	Sales	$	—		$	473.8		$	595.8		$	—		$	1,069.60
	Cost of sales	7.8			465			499.8			—			972.6
	Selling and administrative expenses	27.5			12.2			29			—			68.7
	Income (loss) before interest, other income and income taxes	(35.3		)	(3.4		)	67			—			28.3
	Interest income (expense), net	(26.4		)	(11.3		)	12.5			—			(25.2		)
	Other income (loss) including equity in income of unconsolidated subsidiaries	65.8			0.4			0.5			(65.7		)	1
	Income (loss) from continuing operations before income tax provision (benefit)	4.1			(14.3		)	80			(65.7		)	4.1
	Income tax provision (benefit)	0.5			(4.6		)	23.4			(18.8		)	0.5
	Income (loss) from continuing operations	3.6			(9.7		)	56.6			(46.9		)	3.6
	Income (loss) from discontinued operations, net of tax	(0.7		)	—			(0.7		)	0.7			(0.7		)
	Net income (loss)	2.9			(9.7		)	55.9			(46.2		)	2.9
	Less: Net income attributable to noncontrolling interests	—			—			3.6			—			3.6
	Net income (loss) attributable to ATI	$	2.9		$	(9.7	)	$	52.3		$	(46.2	)	$	(0.7	)
	Comprehensive income (loss) attributable to ATI	$	15.3		$	(7.8	)	$	34.1		$	(31.7	)	$	9.9
	Allegheny Technologies Incorporated
	Financial Information for Subsidiary and Guarantor Parent
	Statements of Operations and Comprehensive Income
	For the nine months ended September 30, 2014
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Sales	$	—		$	1,415.50		$	1,760.40		$	—		$	3,175.90
Cost of sales	34.9			1,429.80			1,454.50			—			2,919.20
Selling and administrative expenses	75.5			32.6			94			—			202.1
Income (loss) before interest, other income and income taxes	(110.4		)	(46.9		)	211.9			—			54.6
Interest income (expense), net	(83.5		)	(33.1		)	33.8			—			(82.8		)
Other income (loss) including equity in income of unconsolidated subsidiaries	168.6			0.9			1.9			(168.5		)	2.9
Income (loss) from continuing operations before income tax provision (benefit)	(25.3		)	(79.1		)	247.6			(168.5		)	(25.3		)
Income tax provision (benefit)	(12.4		)	(27.7		)	88.4			(60.7		)	(12.4		)
Income (loss) from continuing operations	(12.9		)	(51.4		)	159.2			(107.8		)	(12.9		)
Income (loss) from discontinued operations, net of tax	(2.8		)	—			(2.8		)	2.8			(2.8		)
Net income (loss)	(15.7		)	(51.4		)	156.4			(105.0		)	(15.7		)
Less: Net income attributable to noncontrolling interests	—			—			9			—			9
Net income (loss) attributable to ATI	$	(15.7	)	$	(51.4	)	$	147.4		$	(105.0	)	$	(24.7	)
Comprehensive income (loss) attributable to ATI	$	42.7		$	(45.4	)	$	136.8		$	(99.2	)	$	34.9
Condensed Statements of Cash Flows
For the nine months ended September 30, 2014
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Cash flows provided by (used in) operating activities	$	(60.0	)	$	(263.2	)	$	285		$	—		$	(38.2	)
Investing Activities:
Purchases of property, plant and equipment	(0.1		)	(117.2		)	(40.2		)	—			(157.5		)
Purchases of businesses, net of cash acquired	—			—			(92.5		)	—			(92.5		)
Net receipts/(payments) on intercompany activity	—			—			(905.4		)	905.4			—
Asset disposals and other	—			1.6			0.3			—			1.9
Cash flows provided by (used in) investing activities	(0.1		)	(115.6		)	(1,037.8		)	905.4			(248.1		)
Financing Activities:
Payments on long-term debt and capital leases	(397.8		)	(0.1		)	(16.8		)	—			(414.7		)
Net receipts/(payments) on intercompany activity	521.9			383.5			—			(905.4		)	—
Dividends paid to stockholders	(57.8		)	—			—			—			(57.8		)
Other	(3.8		)	—			—			—			(3.8		)
Cash flows provided by (used in) financing activities	62.5			383.4			(16.8		)	(905.4		)	(476.3		)
Increase (decrease) in cash and cash equivalents	$	2.4		$	4.6		$	(769.6	)	$	—		$	(762.6	)
Allegheny Technologies Incorporated
Financial Information for Subsidiary and Guarantor Parent
Balance Sheets
December 31, 2013
	Guarantor						Non-guarantor
(In millions)	Parent			Subsidiary			Subsidiaries			Eliminations			Consolidated
Assets:
Cash and cash equivalents	$	3.6		$	13.5		$	1,009.70		$	—		$	1,026.80
Accounts receivable, net	0.3			179.4			348.5			—			528.2
Intercompany notes receivable	—			—			1,589.40			(1,589.4		)	—
Inventories, net	—			295.5			1,026.60			—			1,322.10
Prepaid expenses and other current assets	26.2			6.5			41			—			73.7
Total current assets	30.1			494.9			4,015.20			(1,589.4		)	2,950.80
Property, plant and equipment, net	2.9			1,397.50			1,473.70			—			2,874.10
Cost in excess of net assets acquired	—			112.1			615.8			—			727.9
Intercompany notes receivable	—			—			200			(200.0		)	—
Investment in subsidiaries	6,170.80			37.7			—			(6,208.5		)	—
Other assets	35.7			32			278			—			345.7
Total assets	$	6,239.50		$	2,074.20		$	6,582.70		$	(7,997.9	)	$	6,898.50
Liabilities and stockholders’ equity:
Accounts payable	$	3.1		$	310.5		$	158.2		$	—		$	471.8
Accrued liabilities	51.6			56.6			207.6			—			315.8
Intercompany notes payable	825.6			763.8			—			(1,589.4		)	—
Deferred income taxes	3.5			—			—			—			3.5
Short-term debt and current portion of long-term debt	402.9			0.1			16.9			—			419.9
Total current liabilities	1,286.70			1,131.00			382.7			(1,589.4		)	1,211.00
Long-term debt	1,350.80			150.4			26.2			—			1,527.40
Intercompany notes payable	—			200			—			(200.0		)	—
Accrued postretirement benefits	—			179.7			262.7			—			442.4
Pension liabilities	323			5.6			39.6			—			368.2
Deferred income taxes	206.6			—			—			—			206.6
Other long-term liabilities	77.7			20.2			50.3			—			148.2
Total liabilities	3,244.80			1,686.90			761.5			(1,789.4		)	3,903.80
Total stockholders’ equity	2,994.70			387.3			5,821.20			(6,208.5		)	2,994.70
Total liabilities and stockholders’ equity	$	6,239.50		$	2,074.20		$	6,582.70		$	(7,997.9	)	$	6,898.50
Allegheny Technologies Incorporated
Financial Information for Subsidiary and Guarantor Parent
Statements of Operations and Comprehensive Income
For the three months ended September 30, 2013
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Sales	$	—		$	422.3		$	550.1		$	—		$	972.4
Cost of sales	19.4			424.3			475.6			—			919.3
Selling and administrative expenses	35.4			7.4			27.8			—			70.6
Income (loss) before interest, other income and income taxes	(54.8		)	(9.4		)	46.7			—			(17.5		)
Interest income (expense), net	(17.3		)	(9.7		)	8.8			—			(18.2		)
Other income (loss) including equity in income of unconsolidated subsidiaries	36.8			0.1			0.3			(36.8		)	0.4
Income (loss) from continuing operations before income tax provision (benefit)	(35.3		)	(19.0		)	55.8			(36.8		)	(35.3		)
Income tax provision (benefit)	(8.5		)	(6.6		)	19.5			(12.9		)	(8.5		)
Income (loss) from continuing operations	(26.8		)	(12.4		)	36.3			(23.9		)	(26.8		)
Income (loss) from discontinued operations, net of tax	(5.4		)	—			(5.4		)	5.4			(5.4		)
Net income (loss)	(32.2		)	(12.4		)	30.9			(18.5		)	(32.2		)
Less: Net income attributable to noncontrolling interests	—			—			1.6			—			1.6
Net income (loss) attributable to ATI	$	(32.2	)	$	(12.4	)	$	29.3		$	(18.5	)	$	(33.8	)
Comprehensive income (loss) attributable to ATI	$	(9.9	)	$	(12.2	)	$	42		$	(31.5	)	$	(11.6	)
Allegheny Technologies Incorporated
Financial Information for Subsidiary and Guarantor Parent
Statements of Operations and Comprehensive Income
For the nine months ended September 30, 2013
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Sales	$	—		$	1,375.20		$	1,753.00		$	—		$	3,128.20
Cost of sales	55.5			1,359.50			1,471.90			—			2,886.90
Selling and administrative expenses	88.9			27.3			93.9			—			210.1
Income (loss) before interest, other income and income taxes	(144.4		)	(11.6		)	187.2			—			31.2
Interest income (expense), net	(45.5		)	(27.0		)	26			—			(46.5		)
Other income (loss) including equity in income of unconsolidated subsidiaries	175.9			0.6			0.8			(176.0		)	1.3
Income (loss) from continuing operations before income tax provision (benefit)	(14.0		)	(38.0		)	214			(176.0		)	(14.0		)
Income tax provision (benefit)	(4.4		)	(9.8		)	72.4			(62.6		)	(4.4		)
Income (loss) from continuing operations	(9.6		)	(28.2		)	141.6			(113.4		)	(9.6		)
Income (loss) from discontinued operations, net of tax	(4.4		)	—			(4.4		)	4.4			(4.4		)
Net income (loss)	(14.0		)	(28.2		)	137.2			(109.0		)	(14.0		)
Less: Net income attributable to noncontrolling interests	—			—			5.4			—			5.4
Net income (loss) attributable to ATI	$	(14.0	)	$	(28.2	)	$	131.8		$	(109.0	)	$	(19.4	)
Comprehensive income (loss) attributable to ATI	$	35.3		$	(27.8	)	$	134.8		$	(114.9	)	$	27.4
Condensed Statements of Cash Flows
For the nine months ended September 30, 2013
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Cash flows provided by (used in) operating activities	$	(27.1	)	$	(87.2	)	$	366		$	(24.3	)	$	227.4
Investing Activities:
Purchases of property, plant and equipment	(0.2		)	(359.1		)	(36.2		)	—			(395.5		)
Net receipts/(payments) on intercompany activity	—			—			(31.4		)	31.4			—
Asset disposals and other	0.1			0.1			0.6			—			0.8
Cash flows provided by (used in) investing activities	(0.1		)	(359.0		)	(67.0		)	31.4			(394.7		)
Financing Activities:
Borrowings on long-term debt	500			—			—			—			500
Net receipts/(payments) on intercompany activity	(409.0		)	440.4			—			(31.4		)	—
Dividends paid to stockholders	(57.7		)	—			(24.3		)	24.3			(57.7		)
Other	(9.0		)	—			(34.9		)	—			(43.9		)
Cash flows provided by (used in) financing activities	24.3			440.4			(59.2		)	(7.1		)	398.4
Increase (decrease) in cash and cash equivalents	$	(2.9	)	$	(5.8	)	$	239.8		$	—		$	231.1
The condensed consolidating statements of cash flows for the nine months ended September 30, 2013 have been revised to reclassify the $18.0 million dividend paid to noncontrolling interest, classified in the Other line of Cash flows from financing activities, to the Non-guarantor Subsidiaries from the Parent. The offset to this change in the Parent and Non-guarantor Cash flows from financing activities is in Cash flows from operating activities.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Accumulated Other Comprehensive Income (Loss)	'
	Accumulated Other Comprehensive Income (Loss)
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the three month period ended September 30, 2014 were as follows (in millions):
		Post-				Currency					Unrealized				Derivatives				Total
		retirement				translation					holding gains
		benefit plans				adjustment					on securities
	Attributable to ATI:
	Balance, June 30, 2014	$	(692.0	)		$	22.7				$	0.1			$	5			$	(664.2	)
	OCI before reclassifications		—				(18.4		)			—				17.2			(1.2		)
	Amounts reclassified from AOCI	(a)	13.4			(b)	—				(b)	—			(c)	(1.6	)		11.8
	Net current-period OCI		13.4				(18.4		)			—				15.6			10.6
	Balance, September 30, 2014	$	(678.6	)		$	4.3				$	0.1			$	20.6			$	(653.6	)
	Attributable to noncontrolling interests:
	Balance, June 30, 2014	$	—			$	$	24.1			$	—			$	—			$	24.1
	OCI before reclassifications		—				1.8					—				—			1.8
	Amounts reclassified from AOCI		—			(b)	—					—				—			—
	Net current-period OCI		—				1.8					—				—			1.8
	Balance, September 30, 2014	$	—			$	25.9				$	—			$	—			$	25.9
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the nine month period ended September 30, 2014 were as follows (in millions):
		Post-				Currency					Unrealized				Derivatives				Total
		retirement				translation					holding gains
		benefit plans				adjustment					on securities
	Attributable to ATI:
	Balance, December 31, 2013	$	(718.9	)		$	15.3				$	—			$	(9.6	)		$	(713.2	)
	OCI before reclassifications		—				(11.0		)			0.1				30.8			19.9
	Amounts reclassified from AOCI	(a)	40.3			(b)	—				(b)	—			(c)	(0.6	)		39.7
	Net current-period OCI		40.3				(11.0		)			0.1				30.2			59.6
	Balance, September 30, 2014	$	(678.6	)		$	4.3				$	0.1			$	20.6			$	(653.6	)
	Attributable to noncontrolling interests:
	Balance, December 31, 2013	$	—			$	$	27.1			$	—			$	—			$	27.1
	OCI before reclassifications		—				(1.2		)			—				—			(1.2		)
	Amounts reclassified from AOCI		—			(b)	—					—				—			—
	Net current-period OCI		—				(1.2		)			—				—			(1.2		)
	Balance, September 30, 2014	$	—			$	25.9				$	—			$	—			$	25.9
	(a)	Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 9).
	(b)	No amounts were reclassified to earnings.
	(c)	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 7).
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the three month period ended September 30, 2013 were as follows (in millions):
		Post-				Currency				Unrealized				Derivatives				Total
		retirement				translation				holding gains
		benefit plans				adjustment				on securities
	Attributable to ATI:
	Balance, June 30, 2013	$	(993.5	)		$	(7.5	)		$	(0.1	)		$	(3.7	)		$	(1,004.8	)
	OCI before reclassifications		—				12.3				0.1				(11.1	)		1.3
	Amounts reclassified from AOCI	(a)	18.3			(b)	—			(b)	—			(c)	2.6			20.9
	Net current-period OCI		18.3				12.3				0.1				(8.5	)		22.2
	Balance, September 30, 2013	$	(975.2	)		$	4.8			$	—			$	(12.2	)		$	(982.6	)
	Attributable to noncontrolling interests:
	Balance, June 30, 2013	$	—			$	26.1			$	—			$	—			$	26.1
	OCI before reclassifications		—				0.1				—				—			0.1
	Amounts reclassified from AOCI		—			(b)	—				—				—			—
	Net current-period OCI		—				0.1				—				—			$	0.1
	Balance, September 30, 2013	$	—			$	26.2			$	—			$	—			$	26.2
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the nine month period ended September 30, 2013 were as follows (in millions):
		Post-				Currency					Unrealized				Derivatives				Total
		retirement				translation					holding gains
		benefit plans				adjustment					on securities
	Attributable to ATI:
	Balance, December 31, 2012	$	(1,030.0	)		$	3.4				$	(0.1	)		$	(2.7	)		$	(1,029.4	)
	OCI before reclassifications		—				1.4					0.1				(12.9	)		(11.4		)
	Amounts reclassified from AOCI	(a)	54.8			(b)	—				(b)	—			(c)	3.4			58.2
	Net current-period OCI		54.8				1.4					0.1				(9.5	)		46.8
	Balance, September 30, 2013	$	(975.2	)		$	4.8				$	—			$	(12.2	)		$	(982.6	)
	Attributable to noncontrolling interests:
Balance, December 31, 2012	$	—			$	$	23.7			$	—			$	—			$	23.7
OCI before reclassifications		—				2.5					—				—			2.5
Amounts reclassified from AOCI		—			(b)	—					—				—			—
Net current-period OCI		—				2.5					—				—			2.5
Balance, September 30, 2013	$	—			$	26.2				$	—			$	—			$	26.2
(a)	Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 9).
(b)	No amounts were reclassified to earnings.
(c)	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 7).
Reclassifications out of AOCI for the three and nine month periods ended September 30, 2014 and September 30, 2013 were as follows:
		Amount reclassified from AOCI (c)
Details about AOCI Components		Three months ended September 30, 2014				Three months ended September 30, 2013				Nine months ended September 30, 2014				Nine months ended September 30, 2013					Affected line item in the
(In millions)																			statements of operations
Postretirement benefit plans
Prior service credit		$	0.2			$	3.8		(a)	$	0.5			$	11.4		(a)
Actuarial losses		(22.1		)		(33.5		)	(a)	(66.1		)		(100.5		)	(a)
		(21.9		)		(29.7		)	(c)	(65.6		)		(89.1		)	(c)		Total before tax
		(8.5		)		(11.4		)		(25.3		)		(34.3		)			Tax provision (benefit)
		$	(13.4	)		$	(18.3	)		$	(40.3	)		$	(54.8	)			Net of tax
Derivatives
Nickel and other raw material contracts		$	2.1			$	(2.3	)	(b)	$	0.8			$	(3.8	)	(b)
Natural gas contracts		—				(0.9		)	(b)	3.9				(2.4		)	(b)
Electricity contracts		(0.1		)		—			(b)	0.7				(0.3		)	(b)
Foreign exchange contracts		0.6				(1.1		)	(b)	(4.4		)		1			(b)
		2.6				(4.3		)	(c)	1				(5.5		)	(c)		Total before tax
		1				(1.7		)		0.4				(2.1		)			Tax provision (benefit)
		$	1.6			$	(2.6	)		$	0.6			$	(3.4	)			Net of tax
(a)	Amounts are included in the computation of pension and other postretirement benefit expense, which is reported in both cost of goods sold and selling and administrative expenses. For additional information, see Note 9.
(b)	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings. For additional information, see Note 7.
(c)	For pretax items, positive amounts are income and negative amounts are expense in terms of the impact to net income. Tax effects are presented in conformity with ATI’s presentation in the consolidated statements of operations.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	The Company is subject to various domestic and international environmental laws and regulations that govern the discharge of pollutants and disposal of wastes, and which may require that it investigate and remediate the effects of the release or disposal of materials at sites associated with past and present operations. The Company could incur substantial cleanup costs, fines, and civil or criminal sanctions, third party property damage or personal injury claims as a result of violations or liabilities under these laws or noncompliance with environmental permits required at its facilities. The Company is currently involved in the investigation and remediation of a number of its current and former sites, as well as third party sites.
	Environmental liabilities are recorded when the Company’s liability is probable and the costs are reasonably estimable. In many cases, however, the Company is not able to determine whether it is liable or, if liability is probable, to reasonably estimate the loss or range of loss. Estimates of the Company’s liability remain subject to additional uncertainties, including the nature and extent of site contamination, available remediation alternatives, the extent of corrective actions that may be required, and the number, participation, and financial condition of other potentially responsible parties (“PRPs”). The Company adjusts its accruals to reflect new information as appropriate. Future adjustments could have a material adverse effect on the Company’s consolidated results of operations in a given period, but the Company cannot reliably predict the amounts of such future adjustments.
	At September 30, 2014, the Company’s reserves for environmental remediation obligations totaled approximately $17 million, of which $9 million was included in other current liabilities. The reserve includes estimated probable future costs of $6 million for federal Superfund and comparable state-managed sites; $9 million for formerly owned or operated sites for which the Company has remediation or indemnification obligations; $1 million for owned or controlled sites at which Company operations have been discontinued; and $1 million for sites utilized by the Company in its ongoing operations. The Company continues to evaluate whether it may be able to recover a portion of past and future costs for environmental liabilities from third parties and to pursue such recoveries where appropriate.
	Based on currently available information, it is reasonably possible that costs for recorded matters may exceed the Company’s recorded reserves by as much as $11 million. However, future investigation or remediation activities may result in the discovery of additional hazardous materials, potentially higher levels of contamination than discovered during prior investigation, and may impact costs of the success or lack thereof in remedial solutions. Therefore, future developments, administrative actions or liabilities relating to environmental matters could have a material adverse effect on the Company’s consolidated financial condition or results of operations.
	The timing of expenditures depends on a number of factors that vary by site. The Company expects that it will expend present accruals over many years and that remediation of all sites with which it has been identified will be completed within thirty years.
	See Note 18. Commitments and Contingencies to the Company’s consolidated financial statements in the Company’s Annual Report on Form 10-K for its fiscal year ended December 31, 2013 for a discussion of legal proceedings affecting the Company.
	A number of other lawsuits, claims and proceedings have been or may be asserted against the Company relating to the conduct of its currently and formerly owned businesses, including those pertaining to product liability, patent infringement, commercial, government contracting, construction, employment, employee and retiree benefits, taxes, environmental, health and safety and occupational disease, and stockholder and corporate governance matters. While the outcome of litigation cannot be predicted with certainty, and some of these lawsuits, claims or proceedings may be determined adversely to the Company, management does not believe that the disposition of any such pending matters is likely to have a material adverse effect on the Company’s financial condition or liquidity, although the resolution in any reporting period of one or more of these matters could have a material adverse effect on the Company’s consolidated results of operations for that period.

Accounting_Policies_Policies

Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2014
Significant Accounting Policies [Abstract]	'
Basis Of Accounting	'
	The interim consolidated financial statements include the accounts of Allegheny Technologies Incorporated and its subsidiaries. Unless the context requires otherwise, “Allegheny Technologies”, “ATI” and “the Company” refer to Allegheny Technologies Incorporated and its subsidiaries.
	These unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and note disclosures required by U.S. generally accepted accounting principles for complete financial statements. In management’s opinion, all adjustments (which include only normal recurring adjustments) considered necessary for a fair presentation have been included. Certain prior year amounts have been reclassified in order to conform with the fiscal year 2014 presentation. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2013 Annual Report on Form 10-K. The results of operations for these interim periods are not necessarily indicative of the operating results for any future period. The December 31, 2013 financial information has been derived from the Company’s audited consolidated financial statements.
New Accounting Pronouncements	'
	New Accounting Pronouncements Adopted
	In January 2014, the Company adopted changes issued by the Financial Accounting Standards Board (FASB) that require an entity to net its liability for unrecognized tax positions against a net operating loss carryforward, a similar tax loss or a tax credit carryforward when settlement in this manner is available under the tax law. The adoption of these changes had no impact on the consolidated financial statements.
	In January 2014, the Company adopted changes issued by the FASB to the accounting for obligations resulting from joint and several liability arrangements. This guidance requires an entity that is joint and severally liable to measure the obligation as the sum of the amount the entity has agreed with co-obligors to pay and any additional amount it expects to pay on behalf of one or more co-obligors. Required disclosures include a description of the nature of the arrangement, how the liability arose, the relationship with co-obligors and the terms and conditions of the arrangement. The adoption of these changes had no impact on the consolidated financial statements.
	In January 2014, the Company adopted changes issued by the FASB to a parent entity’s accounting for the cumulative translation adjustment (CTA) upon derecognition of certain subsidiaries or groups of assets within a foreign entity or of an investment in a foreign entity. The amendments specify that CTA should be released into earnings when an entity ceases to have a controlling financial interest in a subsidiary or group of assets within a consolidated foreign entity and the sale or transfer results in the complete or substantially complete liquidation of the foreign entity. For sales of an equity method investment that is a foreign entity, a pro rata portion of CTA attributable to the investment would be recognized in earnings when the investment is sold. When an entity sells either a part or all of its investment in a consolidated foreign entity, CTA would be recognized in earnings only if the sale results in the parent no longer having a controlling financial interest in the foreign entity. In addition, CTA should be recognized in earnings in a business combination achieved in stages (i.e., a step acquisition). The adoption of these changes had no impact on the consolidated financial statements.
	Pending Accounting Pronouncements
	In May 2014, the FASB issued changes to revenue recognition with customers. This update provides a five-step analysis of transactions to determine when and how revenue is recognized. An entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update will be effective for the Company beginning in fiscal year 2017. This update may be applied retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying this update recognized at the date of initial application. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements.
	In April 2014, the FASB issued changes to the criteria for reporting discontinued operations. Under the new criteria, a disposal of a component of an entity is required to be reported as discontinued operations only if the disposal represents a strategic shift that has, or will have, a major effect on an entity’s operations and financial results. The current criteria that there be no significant continuing involvement in the operations of the component after the disposal transaction has been removed under the new guidance. The new guidance also requires the presentation of the assets and liabilities of a disposal group that includes a discontinued operation for each comparative period and requires additional disclosures about discontinued operations, including the major line items constituting the pretax profit or loss of the discontinued operation, certain cash flow information for the discontinued operation, expanded disclosures about an entity’s significant continuing involvement in a discontinued operation, and disclosures about a disposal of an individually significant component of an entity that does not qualify for discontinued operations presentation. The provisions of the new guidance become effective for all disposals that occur for the Company beginning in fiscal year 2015. The Company does not anticipate a material impact to the consolidated financial statements upon adoption.
Inventory	'
	Inventories are stated at the lower of cost (last-in, first-out (“LIFO”), first-in, first-out (“FIFO”), and average cost methods) or market, less progress payments. Most of the Company’s inventory is valued utilizing the LIFO costing methodology. Inventory of the Company’s non-U.S. operations is valued using average cost or FIFO methods.
Derivatives	'
	For derivative financial instruments that are designated as cash flow hedges, the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive income (OCI) and reclassified into earnings in the same period or periods during which the hedged item affects earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current period results. The Company did not use fair value or net investment hedges for the periods presented. The effects of derivative instruments in the tables below are presented net of related income taxes.
	As part of its risk management strategy, the Company, from time-to-time, utilizes derivative financial instruments to manage its exposure to changes in raw material prices, energy costs, foreign currencies, and interest rates. In accordance with applicable accounting standards, the Company accounts for most of these contracts as hedges. In general, hedge effectiveness is determined by examining the relationship between offsetting changes in fair value or cash flows attributable to the item being hedged, and the financial instrument being used for the hedge. Effectiveness is measured utilizing regression analysis and other techniques to determine whether the change in the fair market value or cash flows of the derivative exceeds the change in fair value or cash flow of the hedged item. Calculated ineffectiveness, if any, is immediately recognized in the consolidated statements of operations.
	The Company sometimes uses futures and swap contracts to manage exposure to changes in prices for forecasted purchases of raw materials, such as nickel and natural gas. Under these contracts, which are generally accounted for as cash flow hedges, the price of the item being hedged is fixed at the time that the contract is entered into and the Company is obligated to make or receive a payment equal to the net change between this fixed price and the market price at the date the contract matures.
	The majority of ATI’s products are sold utilizing raw material surcharges and index mechanisms. However, as of September 30, 2014, the Company had entered into financial hedging arrangements primarily at the request of its customers, related to firm orders, for an aggregate notional amount of approximately 15% of its estimated annual nickel requirements. These nickel hedges extend to 2020.
	At September 30, 2014, the outstanding financial derivatives used to hedge the Company’s exposure to energy cost volatility included natural gas cost hedges for approximately 80% of its annual forecasted domestic requirements for 2014, approximately 85% for 2015, approximately 65% for 2016, and approximately 20% for 2017, and electricity hedges for Western Pennsylvania operations of approximately 10% of its forecasted on-peak and off-peak requirements for 2014.
	While the majority of the Company’s direct export sales are transacted in U.S. dollars, foreign currency exchange contracts are used, from time-to-time, to limit transactional exposure to changes in currency exchange rates for those transactions denominated in a non-U.S. currency. The Company sometimes purchases foreign currency forward contracts that permit it to sell specified amounts of foreign currencies expected to be received from its export sales for pre-established U.S. dollar amounts at specified dates. The forward contracts are denominated in the same foreign currencies in which export sales are denominated. These contracts are designated as hedges of the variability in cash flows of a portion of the forecasted future export sales transactions which otherwise would expose the Company to foreign currency risk. The Company may also enter into foreign currency forward contracts that are not designated as hedges, which are denominated in the same foreign currency in which export sales are denominated. At September 30, 2014, the outstanding financial derivatives, including both hedges and undesignated derivatives, that are used to manage the Company’s exposure to foreign currency, primarily euros, represented approximately 20% of its forecasted total international sales through 2018. In addition, the Company may also designate cash balances held in foreign currencies as hedges of forecasted foreign currency transactions.
	The Company may enter into derivative interest rate contracts to maintain a reasonable balance between fixed- and floating-rate debt. There were no unsettled derivative financial instruments related to debt balances for the periods presented.
	There are no credit risk-related contingent features in the Company’s derivative contracts, and the contracts contained no provisions under which the Company has posted, or would be required to post, collateral. The counterparties to the Company’s derivative contracts are substantial and creditworthy commercial banks that are recognized market makers. The Company controls its credit exposure by diversifying across multiple counterparties and by monitoring credit ratings and credit default swap spreads of its counterparties. The Company also enters into master netting agreements with counterparties when possible.
	The fair values of the Company’s derivative financial instruments are presented below, representing the gross amounts recognized which are not offset by counterparty or by type of item hedged. All fair values for these derivatives were measured using Level 2 information as defined by the accounting standard hierarchy, which includes quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs derived principally from or corroborated by observable market data.
Pension And Other Postretirement Plans	'
	The Company has defined benefit pension plans and defined contribution plans covering substantially all employees. Benefits under the defined benefit pension plans are generally based on years of service and/or final average pay. The Company funds the U.S. pension plans in accordance with the Employee Retirement Income Security Act of 1974, as amended, and the Internal Revenue Code.
	The Company also sponsors several postretirement plans covering certain salaried and hourly employees. The plans provide health care and life insurance benefits for eligible retirees. In most plans, Company contributions towards premiums are capped based on the cost as of a certain date, thereby creating a defined contribution. For the non-collectively bargained plans, the Company maintains the right to amend or terminate the plans at its discretion.
Commitments And Contingencies	'
	Environmental liabilities are recorded when the Company’s liability is probable and the costs are reasonably estimable. In many cases, however, the Company is not able to determine whether it is liable or, if liability is probable, to reasonably estimate the loss or range of loss. Estimates of the Company’s liability remain subject to additional uncertainties, including the nature and extent of site contamination, available remediation alternatives, the extent of corrective actions that may be required, and the number, participation, and financial condition of other potentially responsible parties (“PRPs”). The Company adjusts its accruals to reflect new information as appropriate. Future adjustments could have a material adverse effect on the Company’s consolidated results of operations in a given period, but the Company cannot reliably predict the amounts of such future adjustments.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures	'
	The following table presents summarized operating results for these discontinued operations (in millions):
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Sales	$	3.3		$	77.6		$	14.9		$	236.7
	Loss before income tax benefit	$	(0.5	)	$	(7.1	)	$	(3.5	)	$	(5.4	)

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories at September 30, 2014 and December 31, 2013 were as follows (in millions):
		September 30,			December 31,
		2014			2013
	Raw materials and supplies	$	262.1		$	277.6
	Work-in-process	1,130.70			984.9
	Finished goods	165.5			162.1
	Total inventories at current cost	1,558.30			1,424.60
	Adjustment from current cost to LIFO cost basis	(18.5		)	29.4
	Inventory valuation reserves	(54.5		)	(84.3		)
	Progress payments	(67.6		)	(47.6		)
	Total inventories, net	$	1,417.70		$	1,322.10

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2014
Property, Plant and Equipment [Abstract]	'
Property Plant And Equipment	'
	Property, plant and equipment at September 30, 2014 and December 31, 2013 was as follows (in millions):
		September 30,			December 31,
		2014			2013
	Land	$	30		$	30.2
	Buildings	1,035.40			1,019.10
	Equipment and leasehold improvements	3,668.90			3,526.00
		4,734.30			4,575.30
	Accumulated depreciation and amortization	(1,797.2		)	(1,701.2		)
	Total property, plant and equipment, net	$	2,937.10		$	2,874.10

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Schedule of Debt Instruments	'
	Debt at September 30, 2014 and December 31, 2013 was as follows (in millions):
		September 30,		December 31,
		2014		2013
	Allegheny Technologies 5.875% Notes due 2023	$	500	$	500
	Allegheny Technologies 5.95% Notes due 2021	500		500
	Allegheny Technologies 4.25% Convertible Notes due 2014	—		402.5
	Allegheny Technologies 9.375% Notes due 2019	350		350
	Allegheny Ludlum 6.95% debentures due 2025	150		150
	ATI Ladish Series B 6.14% Notes due 2016 (a)	12		18.2
	ATI Ladish Series C 6.41% Notes due 2015 (b)	10.4		21.1
	Domestic Bank Group $400 million unsecured credit facility	—		—
	Foreign credit facilities	—		—
	Industrial revenue bonds, due through 2020, and other	4.2		5.5
	Total short-term and long-term debt	1,526.60		1,947.30
	Short-term debt and current portion of long-term debt	17.5		419.9
	Total long-term debt	$	1,509.10	$	1,527.40
	(a)	Includes fair value adjustments of $0.6 million at September 30, 2014 and $1.0 million at December 31, 2013.
	(b)	Includes fair value adjustments of $0.4 million at September 30, 2014 and $1.1 million at December 31, 2013.

Derivative_Financial_Instrumen1

Derivative Financial Instruments and Hedging (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule Of Derivative Instruments In Statement Of Financial Position Fair Value	'
	The fair values of the Company’s derivative financial instruments are presented below, representing the gross amounts recognized which are not offset by counterparty or by type of item hedged. All fair values for these derivatives were measured using Level 2 information as defined by the accounting standard hierarchy, which includes quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs derived principally from or corroborated by observable market data.
	(In millions)		Balance sheet location		September 30,				December 31,
	Asset derivatives				2014				2013
	Derivatives designated as hedging instruments:
	Foreign exchange contracts		Prepaid expenses and other current assets		$	14			$	0.3
	Nickel and other raw material contracts		Prepaid expenses and other current assets		3.3				0.1
	Natural gas contracts		Prepaid expenses and other current assets		0.3				2.5
	Foreign exchange contracts		Other assets		20.5				—
	Nickel and other raw material contracts		Other assets		2.4				0.4
	Natural gas contracts		Other assets		0.4				1
	Total derivatives designated as hedging instruments				40.9				4.3
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts		Prepaid expenses and other current assets		4.8				—
	Total derivatives not designated as hedging instruments				4.8				—
	Total asset derivatives				$	45.7			$	4.3
	Liability derivatives		Balance sheet location
	Derivatives designated as hedging instruments:
	Natural gas contracts		Accrued liabilities		$	2.1			$	0.4
	Nickel and other raw material contracts		Accrued liabilities		2.1				4.5
	Foreign exchange contracts		Accrued liabilities		—				7.8
	Electricity contracts		Accrued liabilities		0.1				0.5
	Natural gas contracts		Other long-term liabilities		2.1				—
	Foreign exchange contracts		Other long-term liabilities		—				5.4
	Nickel and other raw material contracts		Other long-term liabilities		1				1.3
	Total derivatives designated as hedging instruments				7.4				19.9
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts		Accrued liabilities		—				1.7
	Total derivatives not designated as hedging instruments				—				1.7
	Total liability derivatives				$	7.4			$	21.6
Schedule Of Derivative Instruments Gain Loss In Statement Of Financial Performance	'
	Activity with regard to derivatives designated as cash flow hedges for the three and nine month periods ended September 30, 2014 and 2013 was as follows (in millions):
		Amount of Gain (Loss)								Amount of Gain (Loss)						Amount of Gain (Loss)
		Recognized in OCI on								Reclassified from						Recognized in Income
		Derivatives								Accumulated OCI						on Derivatives (Ineffective
		(Effective Portion)								into Income						Portion and Amount
										(Effective Portion) (a)						Excluded from
																Effectiveness Testing) (b)
	Derivatives in Cash Flow	Three months ended September 30,								Three months ended September 30,						Three months ended September 30,
	Hedging Relationships	2014				2013				2014			2013			2014		2013
	Nickel and other raw material contracts	$	(4.7	)		$	0.2			$	1.3		$	(1.3	)	$	—	$	—
	Natural gas contracts	(3.0		)		0.1				—			(0.6		)	—		—
	Electricity contracts	(0.2		)		(0.1		)		(0.1		)	—			—		—
	Foreign exchange contracts	25.1				(11.3		)		0.4			(0.7		)	—		—
	Total	$	17.2			$	(11.1	)		$	1.6		$	(2.6	)	$	—	$	—
		Amount of Gain (Loss)								Amount of Gain (Loss)						Amount of Gain (Loss)
		Recognized in OCI on								Reclassified from						Recognized in Income
		Derivatives								Accumulated OCI						on Derivatives (Ineffective
		(Effective Portion)								into Income						Portion and Amount
										(Effective Portion) (a)						Excluded from
																Effectiveness Testing) (b)
	Derivatives in Cash Flow	Nine months ended September 30,								Nine months ended September 30,						Nine months ended September 30,
	Hedging Relationships	2014				2013				2014			2013			2014		2013
	Nickel and other raw material contracts	$	5.4			$	(8.6	)		$	0.5		$	(2.3	)	$	—	$	—
	Natural gas contracts	(1.7		)		(0.2		)		2.4			(1.5		)	—		—
	Electricity contracts	0.6				(0.1		)		0.4			(0.2		)	—		—
	Foreign exchange contracts	26.5				(4.0		)		(2.7		)	0.6			—		—
	Total	$	30.8			$	(12.9	)		$	0.6		$	(3.4	)	$	—	$	—
	(a)	The gains (losses) reclassified from accumulated OCI into income related to the effective portion of the derivatives are presented in cost of sales in the same period or periods in which the hedged item affects earnings.
	(b)	The gains (losses) recognized in income on derivatives related to the ineffective portion and the amount excluded from effectiveness testing are presented in selling and administrative expenses.
Schedule Of Derivative Instruments Not Designated as Hedging Instruments	'
	Derivatives that are not designated as hedging instruments were as follows:
	(In millions)	Amount of Gain (Loss) Recognized
		in Income on Derivatives
	Derivatives Not Designated	Three months ended September 30,								Nine months ended September 30,
	as Hedging Instruments	2014				2013				2014			2013
	Foreign exchange contracts	$	3.1			$	(0.7	)		$	4.2		$	(0.3	)

Recovered_Sheet1

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value By Balance Sheet Grouping	'
	The estimated fair value of financial instruments at September 30, 2014 was as follows:
				Fair Value Measurements at Reporting Date Using
	(In millions)	Total		Total		Quoted Prices in		Significant
		Carrying		Estimated		Active Markets for		Observable
		Amount		Fair Value		Identical Assets(Level 1)		Inputs
								(Level 2)
	Cash and cash equivalents	$	264.2	$	264.2	$	264.2	$	—
	Derivative financial instruments:
	Assets	45.7		45.7		—		45.7
	Liabilities	7.4		7.4		—		7.4
	Debt	1,526.60		1,700.10		1,673.50		26.6
	The estimated fair value of financial instruments at December 31, 2013 was as follows:
				Fair Value Measurements at Reporting Date Using
	(In millions)	Total		Total		Quoted Prices in		Significant
		Carrying		Estimated		Active Markets for		Observable
		Amount		Fair Value		Identical Assets		Inputs
						(Level 1)		(Level 2)
	Cash and cash equivalents	$	1,026.80	$	1,026.80	$	1,026.80	$	—
	Derivative financial instruments:
	Assets	4.3		4.3		—		4.3
	Liabilities	21.6		21.6		—		21.6
	Debt	1,947.30		2,072.60		2,027.80		44.8

Pension_Plans_and_Other_Postre1

Pension Plans and Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Schedule Of Defined Benefit Plans Disclosures	'
	For the three month periods ended September 30, 2014 and 2013, the components of pension expense and components of other postretirement benefit expense for the Company’s defined benefit plans included the following (in millions):
		Pension Benefits						Other Postretirement Benefits
		Three months ended September 30,						Three months ended September 30,
		2014			2013			2014			2013
	Service cost - benefits earned during the year	$	7.3		$	10		$	0.7		$	0.8
	Interest cost on benefits earned in prior years	33.4			30.3			6			5.6
	Expected return on plan assets	(46.1		)	(43.8		)	(0.1		)	(0.1		)
	Amortization of prior service cost (credit)	0.6			0.8			(0.8		)	(4.6		)
	Amortization of net actuarial loss	18.5			29.2			3.6			4.3
	Termination benefits	—			—			—			—
	Total retirement benefit expense	$	13.7		$	26.5		$	9.4		$	6
	For the nine month periods ended September 30, 2014 and 2013, the components of pension expense and components of other postretirement benefit expense for the Company’s defined benefit plans included the following (in millions):
		Pension Benefits						Other Postretirement Benefits
		Nine months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost - benefits earned during the year	$	22		$	30		$	2.1		$	2.4
	Interest cost on benefits earned in prior years	100.2			90.9			18			16.8
	Expected return on plan assets	(138.2		)	(131.4		)	(0.2		)	(0.3		)
	Amortization of prior service cost (credit)	1.8			2.3			(2.3		)	(13.7		)
	Amortization of net actuarial loss	55.5			87.6			10.6			12.9
	Termination benefits	0.3			—			—			—
	Total retirement benefit expense	$	41.6		$	79.4		$	28.2		$	18.1

Business_Segments_Tables

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Schedule Of Segment Reporting Information By Segment	'
	Following is certain financial information with respect to the Company’s business segments for the periods indicated (in millions):
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Total sales:
	High Performance Materials & Components	$	527.1		$	481.2		$	1,562.60		$	1,561.70
	Flat Rolled Products	587			515.6			1,747.10			1,644.00
		1,114.10			996.8			3,309.70			3,205.70
	Intersegment sales:
	High Performance Materials & Components	19.4			17.3			56.4			53.6
	Flat Rolled Products	25.1			7.1			77.4			23.9
		44.5			24.4			133.8			77.5
	Sales to external customers:
	High Performance Materials & Components	507.7			463.9			1,506.20			1,508.10
	Flat Rolled Products	561.9			508.5			1,669.70			1,620.10
		$	1,069.60		$	972.4		$	3,175.90		$	3,128.20
	Operating profit (loss):
	High Performance Materials & Components	$	62		$	48		$	216.2		$	192
	Flat Rolled Products	8.6			(20.4		)	(36.9		)	(16.7		)
	Total operating profit	70.6			27.6			179.3			175.3
	Corporate expenses	(10.0		)	(8.1		)	(33.2		)	(32.3		)
	Interest expense, net	(25.2		)	(18.2		)	(82.8		)	(46.5		)
	Closed company and other expenses	(7.5		)	(2.1		)	(16.8		)	(11.0		)
	Retirement benefit expense	(23.8		)	(34.5		)	(71.8		)	(99.5		)
	Income (loss) from continuing operations before income taxes	$	4.1		$	(35.3	)	$	(25.3	)	$	(14.0	)

Per_Share_Information_Tables

Per Share Information (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Schedule Of Earnings Per Share Diluted By Common Class	'
	The following table sets forth the computation of basic and diluted income from continuing operations per common share:
		Three Months Ended					Nine months ended
	(In millions, except per share amounts)	September 30,					September 30,
		2014		2013			2014			2013
	Numerator for basic income (loss) from continuing operations per common share –
	Income (loss) from continuing operations attributable to ATI	$	—	$	(28.4	)	$	(21.9	)	$	(15.0	)
	Effect of dilutive securities:
	4.25% Convertible Notes due 2014	—		—			—			—
	Numerator for diluted income (loss) from continuing operations per common share –
	Income (loss) from continuing operations available to ATI after assumed conversions	$	—	$	(28.4	)	$	(21.9	)	$	(15.0	)
	Denominator for basic net income (loss) per common share-weighted average shares	107.2		106.8			107.1			106.7
	Effect of dilutive securities:
	Share-based compensation	0.8		—			—			—
	4.25% Convertible Notes due 2014	—		—			—			—
	Denominator for diluted net income (loss) per common share – adjusted weighted average shares assuming conversions	108		106.8			107.1			106.7
	Basic income (loss) from continuing operations attributable to ATI per common share	$	—	$	(0.27	)	$	(0.20	)	$	(0.14	)
	Diluted income (loss) from continuing operations attributable to ATI per common share	$	—	$	(0.27	)	$	(0.20	)	$	(0.14	)

Financial_Information_for_Subs1

Financial Information for Subsidiary and Guarantor Parent (Tables)	9 Months Ended
	Sep. 30, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Condensed Financial Information of Parent Company Only Disclosure	'
	Allegheny Technologies Incorporated
	Financial Information for Subsidiary and Guarantor Parent
	Balance Sheets
	September 30, 2014
	(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
		Parent						Subsidiaries
	Assets:
	Cash and cash equivalents	$	6		$	18.1		$	240.1		$	—		$	264.2
	Accounts receivable, net	0.4			229.5			393.8			—			623.7
	Intercompany notes receivable	—			—			2,534.30			(2,534.3		)	—
	Inventories, net	—			356.8			1,060.90			—			1,417.70
	Prepaid expenses and other current assets	51.8			12.5			45.1			—			109.4
	Total current assets	58.2			616.9			4,274.20			(2,534.3		)	2,415.00
	Property, plant and equipment, net	2.3			1,502.90			1,431.90			—			2,937.10
	Cost in excess of net assets acquired	—			126.6			656.2			—			782.8
	Intercompany notes receivable	—			—			200			(200.0		)	—
	Investment in subsidiaries	6,404.80			37.7			—			(6,442.5		)	—
	Other assets	25.3			28.1			314.9			—			368.3
	Total assets	$	6,490.60		$	2,312.20		$	6,877.20		$	(9,176.8	)	$	6,503.20
	Liabilities and stockholders’ equity:
	Accounts payable	$	5.5		$	299.9		$	177.3		$	—		$	482.7
	Accrued liabilities	38			65.5			202.2			—			305.7
	Intercompany notes payable	1,454.70			1,079.60			—			(2,534.3		)	—
	Deferred income taxes	33.7			—			—			—			33.7
	Short-term debt and current portion of long-term debt	0.5			0.1			16.9			—			17.5
	Total current liabilities	1,532.40			1,445.10			396.4			(2,534.3		)	839.6
	Long-term debt	1,350.70			150.3			8.1			—			1,509.10
	Intercompany notes payable	—			200			—			(200.0		)	—
	Accrued postretirement benefits	—			174.1			246.4			—			420.5
	Pension liabilities	304.2			5.2			39			—			348.4
	Deferred income taxes	244.6			—			—			—			244.6
	Other long-term liabilities	79.1			21.2			49			—			149.3
	Total liabilities	3,511.00			1,995.90			738.9			(2,734.3		)	3,511.50
	Redeemable noncontrolling interest	—			—			12.1			—			12.1
	Total stockholders’ equity	2,979.60			316.3			6,126.20			(6,442.5		)	2,979.60
	Total liabilities and stockholders’ equity	$	6,490.60		$	2,312.20		$	6,877.20		$	(9,176.8	)	$	6,503.20
	Allegheny Technologies Incorporated
	Financial Information for Subsidiary and Guarantor Parent
	Statements of Operations and Comprehensive Income
	For the three months ended September 30, 2014
	(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
		Parent						Subsidiaries
	Sales	$	—		$	473.8		$	595.8		$	—		$	1,069.60
	Cost of sales	7.8			465			499.8			—			972.6
	Selling and administrative expenses	27.5			12.2			29			—			68.7
	Income (loss) before interest, other income and income taxes	(35.3		)	(3.4		)	67			—			28.3
	Interest income (expense), net	(26.4		)	(11.3		)	12.5			—			(25.2		)
	Other income (loss) including equity in income of unconsolidated subsidiaries	65.8			0.4			0.5			(65.7		)	1
	Income (loss) from continuing operations before income tax provision (benefit)	4.1			(14.3		)	80			(65.7		)	4.1
	Income tax provision (benefit)	0.5			(4.6		)	23.4			(18.8		)	0.5
	Income (loss) from continuing operations	3.6			(9.7		)	56.6			(46.9		)	3.6
	Income (loss) from discontinued operations, net of tax	(0.7		)	—			(0.7		)	0.7			(0.7		)
	Net income (loss)	2.9			(9.7		)	55.9			(46.2		)	2.9
	Less: Net income attributable to noncontrolling interests	—			—			3.6			—			3.6
	Net income (loss) attributable to ATI	$	2.9		$	(9.7	)	$	52.3		$	(46.2	)	$	(0.7	)
	Comprehensive income (loss) attributable to ATI	$	15.3		$	(7.8	)	$	34.1		$	(31.7	)	$	9.9
	Allegheny Technologies Incorporated
	Financial Information for Subsidiary and Guarantor Parent
	Statements of Operations and Comprehensive Income
	For the nine months ended September 30, 2014
	(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
		Parent						Subsidiaries
	Sales	$	—		$	1,415.50		$	1,760.40		$	—		$	3,175.90
Cost of sales	34.9			1,429.80			1,454.50			—			2,919.20
Selling and administrative expenses	75.5			32.6			94			—			202.1
Income (loss) before interest, other income and income taxes	(110.4		)	(46.9		)	211.9			—			54.6
Interest income (expense), net	(83.5		)	(33.1		)	33.8			—			(82.8		)
Other income (loss) including equity in income of unconsolidated subsidiaries	168.6			0.9			1.9			(168.5		)	2.9
Income (loss) from continuing operations before income tax provision (benefit)	(25.3		)	(79.1		)	247.6			(168.5		)	(25.3		)
Income tax provision (benefit)	(12.4		)	(27.7		)	88.4			(60.7		)	(12.4		)
Income (loss) from continuing operations	(12.9		)	(51.4		)	159.2			(107.8		)	(12.9		)
Income (loss) from discontinued operations, net of tax	(2.8		)	—			(2.8		)	2.8			(2.8		)
Net income (loss)	(15.7		)	(51.4		)	156.4			(105.0		)	(15.7		)
Less: Net income attributable to noncontrolling interests	—			—			9			—			9
Net income (loss) attributable to ATI	$	(15.7	)	$	(51.4	)	$	147.4		$	(105.0	)	$	(24.7	)
Comprehensive income (loss) attributable to ATI	$	42.7		$	(45.4	)	$	136.8		$	(99.2	)	$	34.9
Condensed Statements of Cash Flows
For the nine months ended September 30, 2014
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Cash flows provided by (used in) operating activities	$	(60.0	)	$	(263.2	)	$	285		$	—		$	(38.2	)
Investing Activities:
Purchases of property, plant and equipment	(0.1		)	(117.2		)	(40.2		)	—			(157.5		)
Purchases of businesses, net of cash acquired	—			—			(92.5		)	—			(92.5		)
Net receipts/(payments) on intercompany activity	—			—			(905.4		)	905.4			—
Asset disposals and other	—			1.6			0.3			—			1.9
Cash flows provided by (used in) investing activities	(0.1		)	(115.6		)	(1,037.8		)	905.4			(248.1		)
Financing Activities:
Payments on long-term debt and capital leases	(397.8		)	(0.1		)	(16.8		)	—			(414.7		)
Net receipts/(payments) on intercompany activity	521.9			383.5			—			(905.4		)	—
Dividends paid to stockholders	(57.8		)	—			—			—			(57.8		)
Other	(3.8		)	—			—			—			(3.8		)
Cash flows provided by (used in) financing activities	62.5			383.4			(16.8		)	(905.4		)	(476.3		)
Increase (decrease) in cash and cash equivalents	$	2.4		$	4.6		$	(769.6	)	$	—		$	(762.6	)
Allegheny Technologies Incorporated
Financial Information for Subsidiary and Guarantor Parent
Balance Sheets
December 31, 2013
	Guarantor						Non-guarantor
(In millions)	Parent			Subsidiary			Subsidiaries			Eliminations			Consolidated
Assets:
Cash and cash equivalents	$	3.6		$	13.5		$	1,009.70		$	—		$	1,026.80
Accounts receivable, net	0.3			179.4			348.5			—			528.2
Intercompany notes receivable	—			—			1,589.40			(1,589.4		)	—
Inventories, net	—			295.5			1,026.60			—			1,322.10
Prepaid expenses and other current assets	26.2			6.5			41			—			73.7
Total current assets	30.1			494.9			4,015.20			(1,589.4		)	2,950.80
Property, plant and equipment, net	2.9			1,397.50			1,473.70			—			2,874.10
Cost in excess of net assets acquired	—			112.1			615.8			—			727.9
Intercompany notes receivable	—			—			200			(200.0		)	—
Investment in subsidiaries	6,170.80			37.7			—			(6,208.5		)	—
Other assets	35.7			32			278			—			345.7
Total assets	$	6,239.50		$	2,074.20		$	6,582.70		$	(7,997.9	)	$	6,898.50
Liabilities and stockholders’ equity:
Accounts payable	$	3.1		$	310.5		$	158.2		$	—		$	471.8
Accrued liabilities	51.6			56.6			207.6			—			315.8
Intercompany notes payable	825.6			763.8			—			(1,589.4		)	—
Deferred income taxes	3.5			—			—			—			3.5
Short-term debt and current portion of long-term debt	402.9			0.1			16.9			—			419.9
Total current liabilities	1,286.70			1,131.00			382.7			(1,589.4		)	1,211.00
Long-term debt	1,350.80			150.4			26.2			—			1,527.40
Intercompany notes payable	—			200			—			(200.0		)	—
Accrued postretirement benefits	—			179.7			262.7			—			442.4
Pension liabilities	323			5.6			39.6			—			368.2
Deferred income taxes	206.6			—			—			—			206.6
Other long-term liabilities	77.7			20.2			50.3			—			148.2
Total liabilities	3,244.80			1,686.90			761.5			(1,789.4		)	3,903.80
Total stockholders’ equity	2,994.70			387.3			5,821.20			(6,208.5		)	2,994.70
Total liabilities and stockholders’ equity	$	6,239.50		$	2,074.20		$	6,582.70		$	(7,997.9	)	$	6,898.50
Allegheny Technologies Incorporated
Financial Information for Subsidiary and Guarantor Parent
Statements of Operations and Comprehensive Income
For the three months ended September 30, 2013
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Sales	$	—		$	422.3		$	550.1		$	—		$	972.4
Cost of sales	19.4			424.3			475.6			—			919.3
Selling and administrative expenses	35.4			7.4			27.8			—			70.6
Income (loss) before interest, other income and income taxes	(54.8		)	(9.4		)	46.7			—			(17.5		)
Interest income (expense), net	(17.3		)	(9.7		)	8.8			—			(18.2		)
Other income (loss) including equity in income of unconsolidated subsidiaries	36.8			0.1			0.3			(36.8		)	0.4
Income (loss) from continuing operations before income tax provision (benefit)	(35.3		)	(19.0		)	55.8			(36.8		)	(35.3		)
Income tax provision (benefit)	(8.5		)	(6.6		)	19.5			(12.9		)	(8.5		)
Income (loss) from continuing operations	(26.8		)	(12.4		)	36.3			(23.9		)	(26.8		)
Income (loss) from discontinued operations, net of tax	(5.4		)	—			(5.4		)	5.4			(5.4		)
Net income (loss)	(32.2		)	(12.4		)	30.9			(18.5		)	(32.2		)
Less: Net income attributable to noncontrolling interests	—			—			1.6			—			1.6
Net income (loss) attributable to ATI	$	(32.2	)	$	(12.4	)	$	29.3		$	(18.5	)	$	(33.8	)
Comprehensive income (loss) attributable to ATI	$	(9.9	)	$	(12.2	)	$	42		$	(31.5	)	$	(11.6	)
Allegheny Technologies Incorporated
Financial Information for Subsidiary and Guarantor Parent
Statements of Operations and Comprehensive Income
For the nine months ended September 30, 2013
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Sales	$	—		$	1,375.20		$	1,753.00		$	—		$	3,128.20
Cost of sales	55.5			1,359.50			1,471.90			—			2,886.90
Selling and administrative expenses	88.9			27.3			93.9			—			210.1
Income (loss) before interest, other income and income taxes	(144.4		)	(11.6		)	187.2			—			31.2
Interest income (expense), net	(45.5		)	(27.0		)	26			—			(46.5		)
Other income (loss) including equity in income of unconsolidated subsidiaries	175.9			0.6			0.8			(176.0		)	1.3
Income (loss) from continuing operations before income tax provision (benefit)	(14.0		)	(38.0		)	214			(176.0		)	(14.0		)
Income tax provision (benefit)	(4.4		)	(9.8		)	72.4			(62.6		)	(4.4		)
Income (loss) from continuing operations	(9.6		)	(28.2		)	141.6			(113.4		)	(9.6		)
Income (loss) from discontinued operations, net of tax	(4.4		)	—			(4.4		)	4.4			(4.4		)
Net income (loss)	(14.0		)	(28.2		)	137.2			(109.0		)	(14.0		)
Less: Net income attributable to noncontrolling interests	—			—			5.4			—			5.4
Net income (loss) attributable to ATI	$	(14.0	)	$	(28.2	)	$	131.8		$	(109.0	)	$	(19.4	)
Comprehensive income (loss) attributable to ATI	$	35.3		$	(27.8	)	$	134.8		$	(114.9	)	$	27.4
Condensed Statements of Cash Flows
For the nine months ended September 30, 2013
(In millions)	Guarantor			Subsidiary			Non-guarantor			Eliminations			Consolidated
	Parent						Subsidiaries
Cash flows provided by (used in) operating activities	$	(27.1	)	$	(87.2	)	$	366		$	(24.3	)	$	227.4
Investing Activities:
Purchases of property, plant and equipment	(0.2		)	(359.1		)	(36.2		)	—			(395.5		)
Net receipts/(payments) on intercompany activity	—			—			(31.4		)	31.4			—
Asset disposals and other	0.1			0.1			0.6			—			0.8
Cash flows provided by (used in) investing activities	(0.1		)	(359.0		)	(67.0		)	31.4			(394.7		)
Financing Activities:
Borrowings on long-term debt	500			—			—			—			500
Net receipts/(payments) on intercompany activity	(409.0		)	440.4			—			(31.4		)	—
Dividends paid to stockholders	(57.7		)	—			(24.3		)	24.3			(57.7		)
Other	(9.0		)	—			(34.9		)	—			(43.9		)
Cash flows provided by (used in) financing activities	24.3			440.4			(59.2		)	(7.1		)	398.4
Increase (decrease) in cash and cash equivalents	$	(2.9	)	$	(5.8	)	$	239.8		$	—		$	231.1

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Schedule Of Accumulated Other Comprehensive Income Loss	'
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the three month period ended September 30, 2014 were as follows (in millions):
		Post-				Currency					Unrealized				Derivatives				Total
		retirement				translation					holding gains
		benefit plans				adjustment					on securities
	Attributable to ATI:
	Balance, June 30, 2014	$	(692.0	)		$	22.7				$	0.1			$	5			$	(664.2	)
	OCI before reclassifications		—				(18.4		)			—				17.2			(1.2		)
	Amounts reclassified from AOCI	(a)	13.4			(b)	—				(b)	—			(c)	(1.6	)		11.8
	Net current-period OCI		13.4				(18.4		)			—				15.6			10.6
	Balance, September 30, 2014	$	(678.6	)		$	4.3				$	0.1			$	20.6			$	(653.6	)
	Attributable to noncontrolling interests:
	Balance, June 30, 2014	$	—			$	$	24.1			$	—			$	—			$	24.1
	OCI before reclassifications		—				1.8					—				—			1.8
	Amounts reclassified from AOCI		—			(b)	—					—				—			—
	Net current-period OCI		—				1.8					—				—			1.8
	Balance, September 30, 2014	$	—			$	25.9				$	—			$	—			$	25.9
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the nine month period ended September 30, 2014 were as follows (in millions):
		Post-				Currency					Unrealized				Derivatives				Total
		retirement				translation					holding gains
		benefit plans				adjustment					on securities
	Attributable to ATI:
	Balance, December 31, 2013	$	(718.9	)		$	15.3				$	—			$	(9.6	)		$	(713.2	)
	OCI before reclassifications		—				(11.0		)			0.1				30.8			19.9
	Amounts reclassified from AOCI	(a)	40.3			(b)	—				(b)	—			(c)	(0.6	)		39.7
	Net current-period OCI		40.3				(11.0		)			0.1				30.2			59.6
	Balance, September 30, 2014	$	(678.6	)		$	4.3				$	0.1			$	20.6			$	(653.6	)
	Attributable to noncontrolling interests:
	Balance, December 31, 2013	$	—			$	$	27.1			$	—			$	—			$	27.1
	OCI before reclassifications		—				(1.2		)			—				—			(1.2		)
	Amounts reclassified from AOCI		—			(b)	—					—				—			—
	Net current-period OCI		—				(1.2		)			—				—			(1.2		)
	Balance, September 30, 2014	$	—			$	25.9				$	—			$	—			$	25.9
	(a)	Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 9).
	(b)	No amounts were reclassified to earnings.
	(c)	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 7).
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the three month period ended September 30, 2013 were as follows (in millions):
		Post-				Currency				Unrealized				Derivatives				Total
		retirement				translation				holding gains
		benefit plans				adjustment				on securities
	Attributable to ATI:
	Balance, June 30, 2013	$	(993.5	)		$	(7.5	)		$	(0.1	)		$	(3.7	)		$	(1,004.8	)
	OCI before reclassifications		—				12.3				0.1				(11.1	)		1.3
	Amounts reclassified from AOCI	(a)	18.3			(b)	—			(b)	—			(c)	2.6			20.9
	Net current-period OCI		18.3				12.3				0.1				(8.5	)		22.2
	Balance, September 30, 2013	$	(975.2	)		$	4.8			$	—			$	(12.2	)		$	(982.6	)
	Attributable to noncontrolling interests:
	Balance, June 30, 2013	$	—			$	26.1			$	—			$	—			$	26.1
	OCI before reclassifications		—				0.1				—				—			0.1
	Amounts reclassified from AOCI		—			(b)	—				—				—			—
	Net current-period OCI		—				0.1				—				—			$	0.1
	Balance, September 30, 2013	$	—			$	26.2			$	—			$	—			$	26.2
	The changes in accumulated other comprehensive income (loss) (AOCI) by component, net of tax, for the nine month period ended September 30, 2013 were as follows (in millions):
		Post-				Currency					Unrealized				Derivatives				Total
		retirement				translation					holding gains
		benefit plans				adjustment					on securities
	Attributable to ATI:
	Balance, December 31, 2012	$	(1,030.0	)		$	3.4				$	(0.1	)		$	(2.7	)		$	(1,029.4	)
	OCI before reclassifications		—				1.4					0.1				(12.9	)		(11.4		)
	Amounts reclassified from AOCI	(a)	54.8			(b)	—				(b)	—			(c)	3.4			58.2
	Net current-period OCI		54.8				1.4					0.1				(9.5	)		46.8
	Balance, September 30, 2013	$	(975.2	)		$	4.8				$	—			$	(12.2	)		$	(982.6	)
	Attributable to noncontrolling interests:
	Balance, December 31, 2012	$	—			$	$	23.7			$	—			$	—			$	23.7
OCI before reclassifications		—				2.5					—				—			2.5
Amounts reclassified from AOCI		—			(b)	—					—				—			—
Net current-period OCI		—				2.5					—				—			2.5
Balance, September 30, 2013	$	—			$	26.2				$	—			$	—			$	26.2
(a)	Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 9).
(b)	No amounts were reclassified to earnings.
(c)	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 7).
Reclassification out of Accumulated Other Comprehensive Income	'
	Reclassifications out of AOCI for the three and nine month periods ended September 30, 2014 and September 30, 2013 were as follows:
			Amount reclassified from AOCI (c)
	Details about AOCI Components		Three months ended September 30, 2014				Three months ended September 30, 2013				Nine months ended September 30, 2014				Nine months ended September 30, 2013					Affected line item in the
	(In millions)																			statements of operations
	Postretirement benefit plans
	Prior service credit		$	0.2			$	3.8		(a)	$	0.5			$	11.4		(a)
	Actuarial losses		(22.1		)		(33.5		)	(a)	(66.1		)		(100.5		)	(a)
			(21.9		)		(29.7		)	(c)	(65.6		)		(89.1		)	(c)		Total before tax
			(8.5		)		(11.4		)		(25.3		)		(34.3		)			Tax provision (benefit)
			$	(13.4	)		$	(18.3	)		$	(40.3	)		$	(54.8	)			Net of tax
	Derivatives
	Nickel and other raw material contracts		$	2.1			$	(2.3	)	(b)	$	0.8			$	(3.8	)	(b)
	Natural gas contracts		—				(0.9		)	(b)	3.9				(2.4		)	(b)
	Electricity contracts		(0.1		)		—			(b)	0.7				(0.3		)	(b)
	Foreign exchange contracts		0.6				(1.1		)	(b)	(4.4		)		1			(b)
			2.6				(4.3		)	(c)	1				(5.5		)	(c)		Total before tax
			1				(1.7		)		0.4				(2.1		)			Tax provision (benefit)
			$	1.6			$	(2.6	)		$	0.6			$	(3.4	)			Net of tax
	(a)	Amounts are included in the computation of pension and other postretirement benefit expense, which is reported in both cost of goods sold and selling and administrative expenses. For additional information, see Note 9.
	(b)	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings. For additional information, see Note 7.
	(c)	For pretax items, positive amounts are income and negative amounts are expense in terms of the impact to net income. Tax effects are presented in conformity with ATI’s presentation in the consolidated statements of operations.

Acquisition_of_Business_Acquis1

Acquisition of Business Acquisition of Business (Details) (USD $)	9 Months Ended			0 Months Ended	9 Months Ended		0 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Feb. 07, 2014	Sep. 30, 2014	Feb. 07, 2014	Jun. 12, 2014	Sep. 30, 2014
				Dynamic Flowform [Member]	Dynamic Flowform [Member]	Dynamic Flowform [Member]	Hanard Machine [Member]	Hanard Machine [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'
Noncontrolling Interest, Ownership Percentage by Parent	'	'	'	'	'	85.00%	'	'
Purchases of businesses, net of cash acquired	($92.50)	$0	'	($72.90)	'	'	($20.50)	($19.60)
Business Acquisition, Remaining Payment	'	'	'	'	'	'	'	-0.9
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	'	'	'	'	'	15.00%	'	'
Business Combination, Acquisition Related Costs	'	'	'	'	0.7	'	'	'
Finite-Lived Intangible Assets, Net	'	'	'	'	'	21.4	4.3	'
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	'	'	'	'23 years	'	'	'20 years	'
Cost in excess of net assets acquired	$782.80	'	$727.90	'	'	$46.80	$8.30	'

Discontinued_Operations_Narrat

Discontinued Operations - Narrative (Details) (USD $)	3 Months Ended			9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2014
		Iron Castings Business	Iron Castings Business	Iron Castings Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'
Severance Costs	'	$0.50	$1.20	$1.70
Restructuring Charge	9.5	'	'	'
Restructuring Charges, Net of Tax	$8.10	'	'	'

Discontinued_Operations_Schedu

Discontinued Operations - Schedule of Income (Loss) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]	'	'	'	'
Sales	$3.30	$77.60	$14.90	$236.70
Loss before income tax benefit	($0.50)	($7.10)	($3.50)	($5.40)

Inventories_Details

Inventories (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Inventory Disclosure [Abstract]	'	'	'
Raw materials and supplies	$262.10	'	$277.60
Work-in-process	1,130.70	'	984.9
Finished goods	165.5	'	162.1
Total inventories at current cost	1,558.30	'	1,424.60
Adjustment from current cost to LIFO cost basis	-18.5	'	29.4
Inventory valuation reserves	-54.5	'	-84.3
Progress payments	-67.6	'	-47.6
Total inventories, net	1,417.70	'	1,322.10
Inventory [Line Items]	'	'	'
Lifo Provision (Benefit)	47.9	-39.1	'
High Performance Materials & Components	'	'	'
Inventory [Line Items]	'	'	'
Change in inventory valuation reserve	-35	'	'
Flat Rolled Products	'	'	'
Inventory [Line Items]	'	'	'
Change in inventory valuation reserve	$18.30	'	'

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Property, Plant and Equipment [Abstract]	'	'
Land	$30	$30.20
Buildings	1,035.40	1,019.10
Equipment and leasehold improvements	3,668.90	3,526
Property Plant And Equipment	4,734.30	4,575.30
Accumulated depreciation and amortization	-1,797.20	-1,701.20
Total property, plant and equipment, net	2,937.10	2,874.10
Construction in progress	$84.10	'

Debt_Schedule_of_Debt_Details

Debt Schedule of Debt (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Total Debt	$1,526,600,000	$1,947,300,000
Short-term debt and current portion of long-term debt	17,500,000	419,900,000
Long-term debt	1,509,100,000	1,527,400,000
Allegheny Technologies 5.875% Notes due 2023	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	500,000,000	500,000,000
Debt Instrument, Issuer	'Allegheny Technologies	'
Debt Instrument, Maturity Date	15-Aug-23	15-Aug-23
Debt Instrument, Interest Rate, Stated Percentage	5.88%	5.88%
Allegheny Technologies 5.95% Notes due 2021	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	500,000,000	500,000,000
Allegheny Technologies 4.25% Convertible Notes due 2014	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	0	402,500,000
Allegheny Technologies 9.375% Notes due 2019	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	350,000,000	350,000,000
Allegheny Ludlum 6.95% debentures due 2025	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	150,000,000	150,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.95%	'
ATI Ladish Series B 6.14% Notes due 2016 (a)	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	12,000,000	18,200,000
Business Acquisition Purchase Price Allocation Notes Payable and L T Debt	600,000	1,000,000
ATI Ladish Series C 6.41% Notes due 2015 (b)	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	10,400,000	21,100,000
Business Acquisition Purchase Price Allocation Notes Payable and L T Debt	400,000	1,100,000
Domestic Bank Group $400 million unsecured credit facility	'	'
Debt Instrument [Line Items]	'	'
Line of Credit Facility, Maximum Borrowing Capacity	400,000,000	'
Long-term Debt, Gross	0	0
Foreign credit facilities	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	0	0
Industrial revenue bonds, due through 2020, and other	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	4,200,000	5,500,000
ATI Ladish Series B 6.14% Notes due 2016 (a)	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Issuer	'ATI Ladish	'
Debt Instrument, Maturity Date	16-May-16	16-May-16
Debt Instrument, Interest Rate, Stated Percentage	6.14%	6.14%
ATI Ladish Series C 6.41% Notes due 2015 (b)	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Issuer	'ATI Ladish	'
Debt Instrument, Maturity Date	2-Sep-15	2-Sep-15
Debt Instrument, Interest Rate, Stated Percentage	6.41%	6.41%
Allegheny Technologies 5.95% Notes due 2021	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Issuer	'Allegheny Technologies	'
Debt Instrument, Maturity Date	15-Jan-21	15-Jan-21
Debt Instrument, Interest Rate, Stated Percentage	5.95%	5.95%
Allegheny Technologies 4.25% Convertible Notes due 2014	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Issuer	'	'Allegheny Technologies
Debt Instrument, Maturity Date	'	1-Jun-14
Debt Instrument, Interest Rate, Stated Percentage	'	4.25%
Industrial revenue bonds, due through 2020, and other	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Maturity Date Range, End	1-Jan-20	1-Jan-20
Allegheny Ludlum 6.95% debentures due 2025	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Issuer	'Allegheny Ludlum	'
Debt Instrument, Maturity Date	15-Dec-25	15-Dec-25
Debt Instrument, Interest Rate, Stated Percentage	'	6.95%
Allegheny Technologies 9.375% Notes due 2019	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Issuer	'Allegheny Technologies	'
Debt Instrument, Maturity Date	1-Jun-19	1-Jun-19
Debt Instrument, Interest Rate, Stated Percentage	9.38%	9.38%
Domestic Bank Group $400 million unsecured credit facility	'	'
Debt Instrument [Line Items]	'	'
Line of Credit Facility, Maximum Borrowing Capacity	'	$400,000,000

Debt_Narrative_Details

Debt Narrative (Details)

9 Months Ended

9 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

USD ($)

USD ($)

Convertible Debt [Member]

Convertible Debt [Member]

Allegheny Technologies 5.875% Notes due 2023

Allegheny Technologies 5.875% Notes due 2023

Domestic Bank Group $400 million unsecured credit facility

Domestic Bank Group $400 million unsecured credit facility

Seperateletter of Credit Facility

STAL Revolving Credit Facility

STAL Revolving Credit Facility

STAL Precision Stainless Steel Company Limited

STAL Revolving Credit Facility

Allegheny Technologies 4.25% Convertible Notes due 2014

Allegheny Technologies 4.25% Convertible Notes due 2014

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

CNY

USD ($)

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Issued During Period, Shares, Conversion of Convertible Securities

'

'

'

'

'

'

'

'

'

'

'

'

'

120,476

'

Debt Instrument, Interest Rate, Stated Percentage

'

'

'

'

5.88%

5.88%

'

'

'

'

'

'

'

'

4.25%

Conversion of convertible notes

$5,000,000

'

'

'

'

'

'

'

'

'

'

'

'

$5,000,000

'

Line of Credit Facility, Maximum Borrowing Capacity

'

'

'

'

'

'

400,000,000

'

'

33,000,000

205,000,000

'

'

'

'

Debt Instrument, Covenant, Maximum Leverage Ratio, Period One

'

'

'

'

'

'

4

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Maximum Leverage Ratio, Period Two

'

'

'

'

'

'

5.75

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Maximum Leverage Ratio, Period Three

'

'

'

'

'

'

5

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Maximum Leverage Ratio, Period Four

'

'

'

'

'

'

4.5

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Maximum Leverage Ratio, Period Five

'

'

'

'

'

'

3.75

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Maximum Leverage Ratio, Period Six

'

'

'

'

'

'

3.5

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Minimum Interest Coverage Ratio, Period One

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Maximum Interest Coverage Ratio, Period Two

'

'

'

'

'

'

2.5

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Maximum Interest Coverage Ratio, Period Three

'

'

'

'

'

'

3

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Minimum Interest Coverage Ratio, Period Four

'

'

'

'

'

'

3.25

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Minimum Interest Coverage Ratio, Period Five

'

'

'

'

'

'

3.5

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Leverage Ratio

'

'

'

'

'

'

2.13

'

'

'

'

'

'

'

'

Debt Instrument, Covenant, Interest Coverage Ratio

'

'

'

'

'

'

4.62

'

'

'

'

'

'

'

'

Amount of Cash on Hand Used to Reduce the Indebtness Figure used in the Leverage Ratio Calculation

'

'

'

'

'

'

50,000,000

'

'

'

'

'

'

'

'

Long-term Debt, Gross

'

'

0

402,500,000

500,000,000

500,000,000

0

0

'

'

'

'

'

'

'

Line of Credit Facility, Amount Outstanding

'

'

'

'

'

'

5,100,000

'

'

'

'

'

'

'

'

Letters of Credit Outstanding, Amount

'

'

'

'

'

'

'

'

32,000,000

'

'

'

'

'

'

Noncontrolling Interest, Ownership Percentage by Parent

'

'

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

Line of Credit Facility, Expiration Date

'

'

'

'

'

'

'

'

'

'

'

'

8-Aug-14

'

'

Debt Instrument, Convertible, Conversion Ratio

'

'

23.9263

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Convertible, Conversion Price

'

'

$41.80

'

'

'

'

'

'

'

'

'

'

'

'

Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities

$414,700,000

$17,000,000

'

'

'

'

'

'

'

'

'

'

'

$397,500,000

'

Derivative_Financial_Instrumen2

Derivative Financial Instruments and Hedging (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Notional Disclosures [Abstract]	'	'	'	'
Percentage of estimated annual nickel requirements	'	'	15.00%	'
Percentage of forecasted natural gas usage hedged for 2014	'	'	80.00%	'
Percentage Of Forecasted Natural Gas Usage Hedged for 2015	'	'	85.00%	'
Percentage Of Forecasted Natural Gas Usage Hedged for 2016	'	'	65.00%	'
Percentage of Forecasted Natural Gas Usage Hedged for 2017	'	'	20.00%	'
Percentage of on-peak and off-peak electricity hedged	'	'	10.00%	'
Percentage of forecasted international sales hedged	'	'	20.00%	'
Reclassification of Cash Flow Hedge Gain (Loss) [Abstract]	'	'	'	'
Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months	'	'	$8.30	'
Other Comprehensive Income | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	17.2	-11.1	30.8	-12.9
Cost Of Sales | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	1.6	-2.6	0.6	-3.4
Selling And Administrative Expenses | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Nickel and other raw material contracts | Other Comprehensive Income | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	-4.7	0.2	5.4	-8.6
Nickel and other raw material contracts | Cost Of Sales | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	1.3	-1.3	0.5	-2.3
Nickel and other raw material contracts | Selling And Administrative Expenses | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Natural gas contracts | Other Comprehensive Income | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	-3	0.1	-1.7	-0.2
Natural gas contracts | Cost Of Sales | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	0	-0.6	2.4	-1.5
Natural gas contracts | Selling And Administrative Expenses | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Electricity contracts | Other Comprehensive Income | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	-0.2	-0.1	0.6	-0.1
Electricity contracts | Cost Of Sales | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	-0.1	0	0.4	-0.2
Electricity contracts | Selling And Administrative Expenses | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Foreign exchange contracts | Other Comprehensive Income | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	25.1	-11.3	26.5	-4
Foreign exchange contracts | Cost Of Sales | Not Designated as Hedging Instrument [Member]	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Income Net	3.1	-0.7	4.2	-0.3
Foreign exchange contracts | Cost Of Sales | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	0.4	-0.7	-2.7	0.6
Foreign exchange contracts | Selling And Administrative Expenses | Cash Flow Hedging	'	'	'	'
Derivative Instruments Gain Loss [Line Items]	'	'	'	'
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	$0	$0	$0	$0

Derivative_Financial_Instrumen3

Derivative Financial Instruments and Hedging (Details2) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	$45.70	$4.30
Derivative Fair Value Of Derivative Liability	7.4	21.6
Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	40.9	4.3
Derivative Fair Value Of Derivative Liability	7.4	19.9
Not Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	4.8	0
Derivative Fair Value Of Derivative Liability	0	1.7
Prepaid expenses and other current assets | Nickel and other raw material contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	3.3	0.1
Prepaid expenses and other current assets | Natural gas contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	0.3	2.5
Prepaid expenses and other current assets | Foreign exchange contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	14	0.3
Prepaid expenses and other current assets | Foreign exchange contracts | Not Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	4.8	0
Other assets | Nickel and other raw material contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	2.4	0.4
Other assets | Natural gas contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	0.4	1
Other assets | Foreign exchange contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Asset	20.5	0
Accrued liabilities | Nickel and other raw material contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	2.1	4.5
Accrued liabilities | Natural gas contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	2.1	0.4
Accrued liabilities | Electricity contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	0.1	0.5
Accrued liabilities | Foreign exchange contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	0	7.8
Accrued liabilities | Foreign exchange contracts | Not Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	0	1.7
Other long-term liabilities | Nickel and other raw material contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	1	1.3
Other long-term liabilities | Natural gas contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	2.1	0
Other long-term liabilities | Foreign exchange contracts | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Fair Value Of Derivative Liability	$0	$5.40

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Carrying Reported Amount Fair Value Disclosure	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	$264.20	$1,026.80
Derivative financial instruments, Assets	45.7	4.3
Derivative Financial Instruments, liabilities	7.4	21.6
Debt	1,526.60	1,947.30
Estimate Of Fair Value Fair Value Disclosure	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	264.2	1,026.80
Derivative financial instruments, Assets	45.7	4.3
Derivative Financial Instruments, liabilities	7.4	21.6
Debt	1,700.10	2,072.60
Fair Value Inputs Level 1	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	264.2	1,026.80
Derivative financial instruments, Assets	0	0
Derivative Financial Instruments, liabilities	0	0
Debt	1,673.50	2,027.80
Fair Value Inputs Level 2	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	0	0
Derivative financial instruments, Assets	45.7	4.3
Derivative Financial Instruments, liabilities	7.4	21.6
Debt	$26.60	$44.80

Pension_Plans_and_Other_Postre2

Pension Plans and Other Postretirement Benefits (Details1) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Plans Defined Benefit	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost - benefits earned during the year	$7.30	$10	$22	$30
Interest cost on benefits earned in prior years	33.4	30.3	100.2	90.9
Expected return on plan assets	-46.1	-43.8	-138.2	-131.4
Amortization of prior service cost (credit)	0.6	0.8	1.8	2.3
Amortization of net actuarial loss	18.5	29.2	55.5	87.6
Termination benefits	0	0	0.3	0
Total retirement benefit expense	13.7	26.5	41.6	79.4
Other Postretirement Benefit Plan, Defined Benefit [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost - benefits earned during the year	0.7	0.8	2.1	2.4
Interest cost on benefits earned in prior years	6	5.6	18	16.8
Expected return on plan assets	-0.1	-0.1	-0.2	-0.3
Amortization of prior service cost (credit)	-0.8	-4.6	-2.3	-13.7
Amortization of net actuarial loss	3.6	4.3	10.6	12.9
Termination benefits	0	0	0	0
Total retirement benefit expense	$9.40	$6	$28.20	$18.10

Pension_Plans_and_Other_Postre3

Pension Plans and Other Postretirement Benefits Narrative (Details) (Other Postretirement Benefit Plan, Defined Benefit [Member], USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other Postretirement Benefit Plan, Defined Benefit [Member]	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'
Defined contribution plan, cost recognized	$0.70	$2	$2	$2

Income_Taxes_Quarterly_Disclos

Income Taxes - Quarterly Disclosure (Details9) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Income tax (provision) benefit	($0.50)	$8.50	$12.40	$4.40
Effective Income Tax Rate Continuing Operations	12.20%	24.10%	49.00%	31.40%
Income Tax Reconciliation Other Adjustments	$3.40	$2.10	$7.80	$6.70
Effective tax rate excluding discrete tax adjustments in period	'	'	18.40%	'

Business_Segments_Details

Business Segments (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Sales	$1,069.60	$972.40	$3,175.90	$3,128.20
Operating profit (loss):	70.6	27.6	179.3	175.3
Corporate expenses	-10	-8.1	-33.2	-32.3
Interest expense, net	-25.2	-18.2	-82.8	-46.5
Closed company and other expenses	-7.5	-2.1	-16.8	-11
Retirement benefit expense	-23.8	-34.5	-71.8	-99.5
Income (loss) from continuing operations before income tax provision (benefit)	4.1	-35.3	-25.3	-14
Interest Costs Capitalized	0.9	12.7	'	'
High Performance Materials & Components	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	507.7	463.9	1,506.20	1,508.10
Operating profit (loss):	62	48	216.2	192
Flat Rolled Products	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	561.9	508.5	1,669.70	1,620.10
Operating profit (loss):	8.6	-20.4	-36.9	-16.7
Operating Segments [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	1,114.10	996.8	3,309.70	3,205.70
Operating Segments [Member] | High Performance Materials & Components	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	527.1	481.2	1,562.60	1,561.70
Operating Segments [Member] | Flat Rolled Products	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	587	515.6	1,747.10	1,644
Intersegment Eliminations [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	44.5	24.4	133.8	77.5
Intersegment Eliminations [Member] | High Performance Materials & Components	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	19.4	17.3	56.4	53.6
Intersegment Eliminations [Member] | Flat Rolled Products	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total sales:	$25.10	$7.10	$77.40	$23.90

Redeemable_Noncontrolling_Inte1

Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Feb. 07, 2014
In Millions, unless otherwise specified			Dynamic Flowform [Member]
Redeemable Noncontrolling Interest [Line Items]	'	'	'
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	'	'	15.00%
Redeemable noncontrolling interest	$12.10	$0	'

Per_Share_Information_Details

Per Share Information (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share Reconciliation [Abstract]	'	'	'	'
Income (loss) from continuing operations attributable to ATI	$0	($28.40)	($21.90)	($15)
4.25% Convertible Notes due 2014	0	0	0	0
Income (loss) from continuing operations available to ATI after assumed conversions	$0	($28.40)	($21.90)	($15)
Denominator for basic net income (loss) per common share-weighted average shares	107,200,000	106,800,000	107,100,000	106,700,000
Share-based compensation	800,000	0	0	0
4.25% Convertible Notes due 2014	0	0	0	0
Denominator for diluted net income (loss) per common share – adjusted weighted average shares assuming conversions	108,000,000	106,800,000	107,100,000	106,700,000
Basic income (loss) from continuing operations attributable to ATI per common share (in dollars per share)	$0	($0.27)	($0.20)	($0.14)
Diluted income (loss) from continuing operations attributable to ATI per common share (in dollars per share)	$0	($0.27)	($0.20)	($0.14)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount	0	10,000,000	6,000,000	10,000,000

Financial_Information_for_Subs2

Financial Information for Subsidiary and Guarantor Parent Financial Information for Subsidiary and Guarantor Parent (Narrative) (Details) (Allegheny Ludlum 6.95% debentures due 2025, USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Allegheny Ludlum 6.95% debentures due 2025	'	'
Debt Instrument [Line Items]	'	'
Long-term Debt, Gross	$150	$150
Interest rate	6.95%	'

Financial_Information_for_Subs3

Financial Information for Subsidiary and Guarantor Parent (B.S.) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
ASSETS	'	'	'	'
Cash and cash equivalents	$264.20	$1,026.80	$535.70	$304.60
Accounts receivable, net	623.7	528.2	'	'
Intercompany notes receivable	0	0	'	'
Inventories, net	1,417.70	1,322.10	'	'
Prepaid expenses and other current assets	109.4	73.7	'	'
Total current assets	2,415	2,950.80	'	'
Property, plant and equipment, net	2,937.10	2,874.10	'	'
Cost in excess of net assets acquired	782.8	727.9	'	'
Intercompany notes receivable	0	0	'	'
Investment in subsidiaries	0	0	'	'
Other assets	368.3	345.7	'	'
Total assets	6,503.20	6,898.50	'	'
LIABILITIES AND EQUITY	'	'	'	'
Accounts payable	482.7	471.8	'	'
Accrued liabilities	305.7	315.8	'	'
Intercompany notes payable	0	0	'	'
Deferred income taxes	33.7	3.5	'	'
Short-term debt and current portion of long-term debt	17.5	419.9	'	'
Total current liabilities	839.6	1,211	'	'
Long-term debt	1,509.10	1,527.40	'	'
Intercompany notes payable	0	0	'	'
Accrued postretirement benefits	420.5	442.4	'	'
Pension liabilities	348.4	368.2	'	'
Deferred income taxes	244.6	206.6	'	'
Other long-term liabilities	149.3	148.2	'	'
Total liabilities	3,511.50	3,903.80	'	'
Redeemable noncontrolling interest	12.1	0	'	'
Total stockholders’ equity	2,979.60	2,994.70	2,564.10	2,587.10
Total Liabilities and Equity	6,503.20	6,898.50	'	'
Parent Company	'	'	'	'
ASSETS	'	'	'	'
Cash and cash equivalents	6	3.6	'	'
Accounts receivable, net	0.4	0.3	'	'
Intercompany notes receivable	0	0	'	'
Inventories, net	0	0	'	'
Prepaid expenses and other current assets	51.8	26.2	'	'
Total current assets	58.2	30.1	'	'
Property, plant and equipment, net	2.3	2.9	'	'
Cost in excess of net assets acquired	0	0	'	'
Intercompany notes receivable	0	0	'	'
Investment in subsidiaries	6,404.80	6,170.80	'	'
Other assets	25.3	35.7	'	'
Total assets	6,490.60	6,239.50	'	'
LIABILITIES AND EQUITY	'	'	'	'
Accounts payable	5.5	3.1	'	'
Accrued liabilities	38	51.6	'	'
Intercompany notes payable	1,454.70	825.6	'	'
Deferred income taxes	33.7	3.5	'	'
Short-term debt and current portion of long-term debt	0.5	402.9	'	'
Total current liabilities	1,532.40	1,286.70	'	'
Long-term debt	1,350.70	1,350.80	'	'
Intercompany notes payable	0	0	'	'
Accrued postretirement benefits	0	0	'	'
Pension liabilities	304.2	323	'	'
Deferred income taxes	244.6	206.6	'	'
Other long-term liabilities	79.1	77.7	'	'
Total liabilities	3,511	3,244.80	'	'
Redeemable noncontrolling interest	0	'	'	'
Total stockholders’ equity	2,979.60	2,994.70	'	'
Total Liabilities and Equity	6,490.60	6,239.50	'	'
Subsidiaries	'	'	'	'
ASSETS	'	'	'	'
Cash and cash equivalents	18.1	13.5	'	'
Accounts receivable, net	229.5	179.4	'	'
Intercompany notes receivable	0	0	'	'
Inventories, net	356.8	295.5	'	'
Prepaid expenses and other current assets	12.5	6.5	'	'
Total current assets	616.9	494.9	'	'
Property, plant and equipment, net	1,502.90	1,397.50	'	'
Cost in excess of net assets acquired	126.6	112.1	'	'
Intercompany notes receivable	0	0	'	'
Investment in subsidiaries	37.7	37.7	'	'
Other assets	28.1	32	'	'
Total assets	2,312.20	2,074.20	'	'
LIABILITIES AND EQUITY	'	'	'	'
Accounts payable	299.9	310.5	'	'
Accrued liabilities	65.5	56.6	'	'
Intercompany notes payable	1,079.60	763.8	'	'
Deferred income taxes	0	0	'	'
Short-term debt and current portion of long-term debt	0.1	0.1	'	'
Total current liabilities	1,445.10	1,131	'	'
Long-term debt	150.3	150.4	'	'
Intercompany notes payable	200	200	'	'
Accrued postretirement benefits	174.1	179.7	'	'
Pension liabilities	5.2	5.6	'	'
Deferred income taxes	0	0	'	'
Other long-term liabilities	21.2	20.2	'	'
Total liabilities	1,995.90	1,686.90	'	'
Redeemable noncontrolling interest	0	'	'	'
Total stockholders’ equity	316.3	387.3	'	'
Total Liabilities and Equity	2,312.20	2,074.20	'	'
NonGuarantor Subsidiaries	'	'	'	'
ASSETS	'	'	'	'
Cash and cash equivalents	240.1	1,009.70	'	'
Accounts receivable, net	393.8	348.5	'	'
Intercompany notes receivable	2,534.30	1,589.40	'	'
Inventories, net	1,060.90	1,026.60	'	'
Prepaid expenses and other current assets	45.1	41	'	'
Total current assets	4,274.20	4,015.20	'	'
Property, plant and equipment, net	1,431.90	1,473.70	'	'
Cost in excess of net assets acquired	656.2	615.8	'	'
Intercompany notes receivable	200	200	'	'
Investment in subsidiaries	0	0	'	'
Other assets	314.9	278	'	'
Total assets	6,877.20	6,582.70	'	'
LIABILITIES AND EQUITY	'	'	'	'
Accounts payable	177.3	158.2	'	'
Accrued liabilities	202.2	207.6	'	'
Intercompany notes payable	0	0	'	'
Deferred income taxes	0	0	'	'
Short-term debt and current portion of long-term debt	16.9	16.9	'	'
Total current liabilities	396.4	382.7	'	'
Long-term debt	8.1	26.2	'	'
Intercompany notes payable	0	0	'	'
Accrued postretirement benefits	246.4	262.7	'	'
Pension liabilities	39	39.6	'	'
Deferred income taxes	0	0	'	'
Other long-term liabilities	49	50.3	'	'
Total liabilities	738.9	761.5	'	'
Redeemable noncontrolling interest	12.1	'	'	'
Total stockholders’ equity	6,126.20	5,821.20	'	'
Total Liabilities and Equity	6,877.20	6,582.70	'	'
Consolidation Eliminations	'	'	'	'
ASSETS	'	'	'	'
Cash and cash equivalents	0	0	'	'
Accounts receivable, net	0	0	'	'
Intercompany notes receivable	-2,534.30	-1,589.40	'	'
Inventories, net	0	0	'	'
Prepaid expenses and other current assets	0	0	'	'
Total current assets	-2,534.30	-1,589.40	'	'
Property, plant and equipment, net	0	0	'	'
Cost in excess of net assets acquired	0	0	'	'
Intercompany notes receivable	-200	-200	'	'
Investment in subsidiaries	-6,442.50	-6,208.50	'	'
Other assets	0	0	'	'
Total assets	-9,176.80	-7,997.90	'	'
LIABILITIES AND EQUITY	'	'	'	'
Accounts payable	0	0	'	'
Accrued liabilities	0	0	'	'
Intercompany notes payable	-2,534.30	-1,589.40	'	'
Deferred income taxes	0	0	'	'
Short-term debt and current portion of long-term debt	0	0	'	'
Total current liabilities	-2,534.30	-1,589.40	'	'
Long-term debt	0	0	'	'
Intercompany notes payable	-200	-200	'	'
Accrued postretirement benefits	0	0	'	'
Pension liabilities	0	0	'	'
Deferred income taxes	0	0	'	'
Other long-term liabilities	0	0	'	'
Total liabilities	-2,734.30	-1,789.40	'	'
Redeemable noncontrolling interest	0	'	'	'
Total stockholders’ equity	-6,442.50	-6,208.50	'	'
Total Liabilities and Equity	($9,176.80)	($7,997.90)	'	'

Financial_Information_for_Subs4

Financial Information for Subsidiary and Guarantor Parent (I.S.) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]	'	'	'	'
Sales	$1,069.60	$972.40	$3,175.90	$3,128.20
Cost of sales	972.6	919.3	2,919.20	2,886.90
Selling and administrative expenses	68.7	70.6	202.1	210.1
Income (loss) before interest, other income and income taxes	28.3	-17.5	54.6	31.2
Interest income (expense), net	-25.2	-18.2	-82.8	-46.5
Other income (loss) including equity in income of unconsolidated subsidiaries	1	0.4	2.9	1.3
Income (loss) from continuing operations before income tax provision (benefit)	4.1	-35.3	-25.3	-14
Income tax provision (benefit)	0.5	-8.5	-12.4	-4.4
Income (loss) from continuing operations	3.6	-26.8	-12.9	-9.6
Income (loss) from discontinued operations, net of tax	-0.7	-5.4	-2.8	-4.4
Net income (loss)	2.9	-32.2	-15.7	-14
Less: Net income attributable to noncontrolling interests	3.6	1.6	9	5.4
Net income (loss) attributable to ATI	-0.7	-33.8	-24.7	-19.4
Comprehensive income (loss) attributable to ATI	9.9	-11.6	34.9	27.4
Parent Company	'	'	'	'
Income Statement [Abstract]	'	'	'	'
Sales	0	0	0	0
Cost of sales	7.8	19.4	34.9	55.5
Selling and administrative expenses	27.5	35.4	75.5	88.9
Income (loss) before interest, other income and income taxes	-35.3	-54.8	-110.4	-144.4
Interest income (expense), net	-26.4	-17.3	-83.5	-45.5
Other income (loss) including equity in income of unconsolidated subsidiaries	65.8	36.8	168.6	175.9
Income (loss) from continuing operations before income tax provision (benefit)	4.1	-35.3	-25.3	-14
Income tax provision (benefit)	0.5	-8.5	-12.4	-4.4
Income (loss) from continuing operations	3.6	-26.8	-12.9	-9.6
Income (loss) from discontinued operations, net of tax	-0.7	-5.4	-2.8	-4.4
Net income (loss)	2.9	-32.2	-15.7	-14
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to ATI	2.9	-32.2	-15.7	-14
Comprehensive income (loss) attributable to ATI	15.3	-9.9	42.7	35.3
Subsidiaries	'	'	'	'
Income Statement [Abstract]	'	'	'	'
Sales	473.8	422.3	1,415.50	1,375.20
Cost of sales	465	424.3	1,429.80	1,359.50
Selling and administrative expenses	12.2	7.4	32.6	27.3
Income (loss) before interest, other income and income taxes	-3.4	-9.4	-46.9	-11.6
Interest income (expense), net	-11.3	-9.7	-33.1	-27
Other income (loss) including equity in income of unconsolidated subsidiaries	0.4	0.1	0.9	0.6
Income (loss) from continuing operations before income tax provision (benefit)	-14.3	-19	-79.1	-38
Income tax provision (benefit)	-4.6	-6.6	-27.7	-9.8
Income (loss) from continuing operations	-9.7	-12.4	-51.4	-28.2
Income (loss) from discontinued operations, net of tax	0	0	0	0
Net income (loss)	-9.7	-12.4	-51.4	-28.2
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to ATI	-9.7	-12.4	-51.4	-28.2
Comprehensive income (loss) attributable to ATI	-7.8	-12.2	-45.4	-27.8
NonGuarantor Subsidiaries	'	'	'	'
Income Statement [Abstract]	'	'	'	'
Sales	595.8	550.1	1,760.40	1,753
Cost of sales	499.8	475.6	1,454.50	1,471.90
Selling and administrative expenses	29	27.8	94	93.9
Income (loss) before interest, other income and income taxes	67	46.7	211.9	187.2
Interest income (expense), net	12.5	8.8	33.8	26
Other income (loss) including equity in income of unconsolidated subsidiaries	0.5	0.3	1.9	0.8
Income (loss) from continuing operations before income tax provision (benefit)	80	55.8	247.6	214
Income tax provision (benefit)	23.4	19.5	88.4	72.4
Income (loss) from continuing operations	56.6	36.3	159.2	141.6
Income (loss) from discontinued operations, net of tax	-0.7	-5.4	-2.8	-4.4
Net income (loss)	55.9	30.9	156.4	137.2
Less: Net income attributable to noncontrolling interests	3.6	1.6	9	5.4
Net income (loss) attributable to ATI	52.3	29.3	147.4	131.8
Comprehensive income (loss) attributable to ATI	34.1	42	136.8	134.8
Consolidation Eliminations	'	'	'	'
Income Statement [Abstract]	'	'	'	'
Sales	0	0	0	0
Cost of sales	0	0	0	0
Selling and administrative expenses	0	0	0	0
Income (loss) before interest, other income and income taxes	0	0	0	0
Interest income (expense), net	0	0	0	0
Other income (loss) including equity in income of unconsolidated subsidiaries	-65.7	-36.8	-168.5	-176
Income (loss) from continuing operations before income tax provision (benefit)	-65.7	-36.8	-168.5	-176
Income tax provision (benefit)	-18.8	-12.9	-60.7	-62.6
Income (loss) from continuing operations	-46.9	-23.9	-107.8	-113.4
Income (loss) from discontinued operations, net of tax	0.7	5.4	2.8	4.4
Net income (loss)	-46.2	-18.5	-105	-109
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income (loss) attributable to ATI	-46.2	-18.5	-105	-109
Comprehensive income (loss) attributable to ATI	($31.70)	($31.50)	($99.20)	($114.90)

Financial_Information_for_Subs5

Financial Information for Subsidiary and Guarantor Parent (Cash Flow) (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Statement of Cash Flows	'	'
Cash flows provided by (used in) operating activities	($38.20)	$227.40
Investing Activities:	'	'
Purchases of property, plant and equipment	-157.5	-395.5
Purchases of businesses, net of cash acquired	-92.5	0
Net receipts/(payments) on intercompany activity	0	0
Asset disposals and other	1.9	0.8
Cash used in investing activities	-248.1	-394.7
Borrowings on long-term debt	0	500
Financing Activities:	'	'
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	-414.7	-17
Net receipts/(payments) on intercompany activity	0	0
Dividends paid to stockholders	-57.8	-57.7
Other	-3.8	-43.9
Cash provided by (used in) financing activities	-476.3	398.4
Increase (decrease) in cash and cash equivalents	-762.6	231.1
Parent Company	'	'
Statement of Cash Flows	'	'
Cash flows provided by (used in) operating activities	-60	-27.1
Investing Activities:	'	'
Purchases of property, plant and equipment	-0.1	-0.2
Purchases of businesses, net of cash acquired	0	'
Net receipts/(payments) on intercompany activity	0	0
Asset disposals and other	0	0.1
Cash used in investing activities	-0.1	-0.1
Borrowings on long-term debt	'	500
Financing Activities:	'	'
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	-397.8	'
Net receipts/(payments) on intercompany activity	521.9	-409
Dividends paid to stockholders	-57.8	-57.7
Other	-3.8	-9
Cash provided by (used in) financing activities	62.5	24.3
Increase (decrease) in cash and cash equivalents	2.4	-2.9
Subsidiaries	'	'
Statement of Cash Flows	'	'
Cash flows provided by (used in) operating activities	-263.2	-87.2
Investing Activities:	'	'
Purchases of property, plant and equipment	-117.2	-359.1
Purchases of businesses, net of cash acquired	0	'
Net receipts/(payments) on intercompany activity	0	0
Asset disposals and other	1.6	0.1
Cash used in investing activities	-115.6	-359
Borrowings on long-term debt	'	0
Financing Activities:	'	'
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	-0.1	'
Net receipts/(payments) on intercompany activity	383.5	440.4
Dividends paid to stockholders	0	0
Other	0	0
Cash provided by (used in) financing activities	383.4	440.4
Increase (decrease) in cash and cash equivalents	4.6	-5.8
NonGuarantor Subsidiaries	'	'
Statement of Cash Flows	'	'
Cash flows provided by (used in) operating activities	285	366
Investing Activities:	'	'
Purchases of property, plant and equipment	-40.2	-36.2
Purchases of businesses, net of cash acquired	-92.5	'
Net receipts/(payments) on intercompany activity	-905.4	-31.4
Asset disposals and other	0.3	0.6
Cash used in investing activities	-1,037.80	-67
Borrowings on long-term debt	'	0
Financing Activities:	'	'
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	-16.8	'
Net receipts/(payments) on intercompany activity	0	0
Dividends paid to stockholders	0	-24.3
Other	0	-34.9
Cash provided by (used in) financing activities	-16.8	-59.2
Increase (decrease) in cash and cash equivalents	-769.6	239.8
Consolidation Eliminations	'	'
Statement of Cash Flows	'	'
Cash flows provided by (used in) operating activities	0	-24.3
Investing Activities:	'	'
Purchases of property, plant and equipment	0	0
Purchases of businesses, net of cash acquired	0	'
Net receipts/(payments) on intercompany activity	905.4	31.4
Asset disposals and other	0	0
Cash used in investing activities	905.4	31.4
Borrowings on long-term debt	'	0
Financing Activities:	'	'
Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities	0	'
Net receipts/(payments) on intercompany activity	-905.4	-31.4
Dividends paid to stockholders	0	24.3
Other	0	0
Cash provided by (used in) financing activities	-905.4	-7.1
Increase (decrease) in cash and cash equivalents	$0	$0

Financial_Information_for_Subs6

Financial Information for Subsidiary and Guarantor Parent Financial Information for Subsidiary and Guarantor Parent (Changes) (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Payments of Ordinary Dividends, Noncontrolling Interest	$0	$18	'	'
Current assets	2,415	'	2,950.80	'
Assets	6,503.20	'	6,898.50	'
Current liabilities	839.6	'	1,211	'
Liabilities	3,511.50	'	3,903.80	'
Stockholders' equity	2,979.60	2,564.10	2,994.70	2,587.10
Cash flows provided by (used in) operating activities	-38.2	227.4	'	'
Net Cash Provided by (Used in) Investing Activities	-248.1	-394.7	'	'
Cash provided by (used in) financing activities	-476.3	398.4	'	'
NonGuarantor Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Current assets	4,274.20	'	4,015.20	'
Assets	6,877.20	'	6,582.70	'
Current liabilities	396.4	'	382.7	'
Liabilities	738.9	'	761.5	'
Stockholders' equity	6,126.20	'	5,821.20	'
Cash flows provided by (used in) operating activities	285	366	'	'
Net Cash Provided by (Used in) Investing Activities	-1,037.80	-67	'	'
Cash provided by (used in) financing activities	-16.8	-59.2	'	'
Subsidiaries	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Current assets	616.9	'	494.9	'
Assets	2,312.20	'	2,074.20	'
Current liabilities	1,445.10	'	1,131	'
Liabilities	1,995.90	'	1,686.90	'
Stockholders' equity	316.3	'	387.3	'
Cash flows provided by (used in) operating activities	-263.2	-87.2	'	'
Net Cash Provided by (Used in) Investing Activities	-115.6	-359	'	'
Cash provided by (used in) financing activities	383.4	440.4	'	'
Parent Company	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Current assets	58.2	'	30.1	'
Assets	6,490.60	'	6,239.50	'
Current liabilities	1,532.40	'	1,286.70	'
Liabilities	3,511	'	3,244.80	'
Stockholders' equity	2,979.60	'	2,994.70	'
Cash flows provided by (used in) operating activities	-60	-27.1	'	'
Net Cash Provided by (Used in) Investing Activities	-0.1	-0.1	'	'
Cash provided by (used in) financing activities	62.5	24.3	'	'
Consolidation Eliminations	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Current assets	-2,534.30	'	-1,589.40	'
Assets	-9,176.80	'	-7,997.90	'
Current liabilities	-2,534.30	'	-1,589.40	'
Liabilities	-2,734.30	'	-1,789.40	'
Stockholders' equity	-6,442.50	'	-6,208.50	'
Cash flows provided by (used in) operating activities	0	-24.3	'	'
Net Cash Provided by (Used in) Investing Activities	905.4	31.4	'	'
Cash provided by (used in) financing activities	($905.40)	($7.10)	'	'

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'		'		'		'
Beginning balance	($664.20)		($1,004.80)		($713.20)		($1,029.40)
OCI before reclassifications	-1.2		1.3		19.9		-11.4
Amounts reclassified from AOCI	11.8		20.9		39.7		58.2
Net current-period OCI	10.6		22.2		59.6		46.8
Ending balance	-653.6		-982.6		-653.6		-982.6
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]	'		'		'		'
Beginning balance	24.1		26.1		27.1		23.7
OCI before reclassifications	1.8		0.1		-1.2		2.5
Amounts reclassified from AOCI	0		0		0		0
Net current-period OCI	1.8		0.1		-1.2		2.5
Ending balance	25.9		26.2		25.9		26.2
Post- retirement benefit plans [Member]	'		'		'		'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'		'		'		'
Beginning balance	-692		-993.5		-718.9		-1,030
OCI before reclassifications	0		0		0		0
Amounts reclassified from AOCI	13.4	[1]	18.3	[1]	40.3	[1]	54.8	[1]
Net current-period OCI	13.4		18.3		40.3		54.8
Ending balance	-678.6		-975.2		-678.6		-975.2
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]	'		'		'		'
Beginning balance	0		0		0		0
OCI before reclassifications	0		0		0		0
Amounts reclassified from AOCI	0		0		0		0
Net current-period OCI	0		0		0		0
Ending balance	0		0		0		0
Currency translation adjustment [Member]	'		'		'		'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'		'		'		'
Beginning balance	22.7		-7.5		15.3		3.4
OCI before reclassifications	-18.4		12.3		-11		1.4
Amounts reclassified from AOCI	0	[2]	0	[2]	0	[2]	0	[2]
Net current-period OCI	-18.4		12.3		-11		1.4
Ending balance	4.3		4.8		4.3		4.8
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]	'		'		'		'
Beginning balance	24.1		26.1		27.1		23.7
OCI before reclassifications	1.8		0.1		-1.2		2.5
Amounts reclassified from AOCI	0	[2]	0	[2]	0	[2]	0	[2]
Net current-period OCI	1.8		0.1		-1.2		2.5
Ending balance	25.9		26.2		25.9		26.2
Unrealized holding gains on securities [Member]	'		'		'		'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'		'		'		'
Beginning balance	0.1		-0.1		0		-0.1
OCI before reclassifications	0		0.1		0.1		0.1
Amounts reclassified from AOCI	0	[2]	0	[2]	0	[2]	0	[2]
Net current-period OCI	0		0.1		0.1		0.1
Ending balance	0.1		0		0.1		0
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]	'		'		'		'
Beginning balance	0		0		0		0
OCI before reclassifications	0		0		0		0
Amounts reclassified from AOCI	0		0		0		0
Net current-period OCI	0		0		0		0
Ending balance	0		0		0		0
Derivatives [Member]	'		'		'		'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'		'		'		'
Beginning balance	5		-3.7		-9.6		-2.7
OCI before reclassifications	17.2		-11.1		30.8		-12.9
Amounts reclassified from AOCI	-1.6	[3]	2.6	[3]	-0.6	[3]	3.4	[3]
Net current-period OCI	15.6		-8.5		30.2		-9.5
Ending balance	20.6		-12.2		20.6		-12.2
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]	'		'		'		'
Beginning balance	0		0		0		0
OCI before reclassifications	0		0		0		0
Amounts reclassified from AOCI	0		0		0		0
Net current-period OCI	0		0		0		0
Ending balance	$0		$0		$0		$0
[1]	Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 9).
[2]	No amounts were reclassified to earnings.
[3]	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 7).

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income (Loss) (Details 2) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Amortization to net income of net prior service credits	($0.20)		($3.80)		($0.50)		($11.40)
Amount reclassified from AOCI, Postretirement benefit plans, Actuarial losses	22.1		33.5		66.1		100.5
Income (loss) from continuing operations before income tax provision (benefit)	4.1		-35.3		-25.3		-14
Income tax provision (benefit)	0.5		-8.5		-12.4		-4.4
Income (loss) from continuing operations	3.6		-26.8		-12.9		-9.6
Amount reclassified from AOCI, Gain (loss) on derivatives	-972.6		-919.3		-2,919.20		-2,886.90
Reclassification out of Accumulated Other Comprehensive Income [Member] | Post- retirement benefit plans [Member]	'		'		'		'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Amortization to net income of net prior service credits	0.2	[1]	3.8	[1]	0.5	[1]	11.4	[1]
Amount reclassified from AOCI, Postretirement benefit plans, Actuarial losses	-22.1	[1]	-33.5	[1]	-66.1	[1]	-100.5	[1]
Income (loss) from continuing operations before income tax provision (benefit)	-21.9	[2]	-29.7	[2]	-65.6	[2]	-89.1	[2]
Income tax provision (benefit)	-8.5		-11.4		-25.3		-34.3
Income (loss) from continuing operations	-13.4		-18.3		-40.3		-54.8
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member]	'		'		'		'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Income (loss) from continuing operations before income tax provision (benefit)	2.6	[2]	-4.3	[2]	1	[2]	-5.5	[2]
Income tax provision (benefit)	1		-1.7		0.4		-2.1
Income (loss) from continuing operations	1.6		-2.6		0.6		-3.4
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member] | Nickel and other raw material contracts	'		'		'		'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Amount reclassified from AOCI, Gain (loss) on derivatives	2.1	[3]	-2.3	[3]	0.8	[3]	-3.8	[3]
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member] | Natural gas contracts	'		'		'		'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Amount reclassified from AOCI, Gain (loss) on derivatives	0	[3]	-0.9	[3]	3.9	[3]	-2.4	[3]
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member] | Electricity contracts	'		'		'		'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Amount reclassified from AOCI, Gain (loss) on derivatives	-0.1	[3]	0	[3]	0.7	[3]	-0.3	[3]
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member] | Foreign exchange contracts	'		'		'		'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Amount reclassified from AOCI, Gain (loss) on derivatives	$0.60	[3]	($1.10)	[3]	($4.40)	[3]	$1	[3]
[1]	Amounts are included in the computation of pension and other postretirement benefit expense, which is reported in both cost of goods sold and selling and administrative expenses. For additional information, see Note 9.
[2]	For pretax items, positive amounts are income and negative amounts are expense in terms of the impact to net income. Tax effects are presented in conformity with ATI’s presentation in the consolidated statements of operations.
[3]	Amounts are included in cost of goods sold in the period or periods the hedged item affects earnings. For additional information, see Note 7.

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	Sep. 30, 2014
In Millions, unless otherwise specified
Components of Environmental Loss Accrual [Abstract]	'
Accrual For Environmental Loss Contingencies	$17
Accrued Environmental Loss Contingencies Current	9
Federal Superfund and comparable state-managed sites	6
Formerly owned or operated sites	9
Owned or controlled sites at which Company operations have been discontinued	1
Sites utilized by the company in its ongoing operations	1
Loss Contingency, Estimate [Abstract]	'
Loss contingency maximum possible loss	$11