ATI (ATI) 10-Q 30 Apr 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	3 Months Ended
	Mar. 31, 2019	Apr. 19, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Entity Registrant Name	ALLEGHENY TECHNOLOGIES INCORPORATED
Entity Central Index Key	0001018963
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		126,034,880
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Public Float			$ 3.2

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 217	$ 382
Accounts receivable, net	565.1	527.8
Short-term contract assets	48.7	51.2
Inventories, net	1,254.4	1,211.1
Prepaid expenses and other current assets	92.7	74.6
Total current assets	2,177.9	2,246.7
Property, plant and equipment, net	2,470.7	2,475
Goodwill	536.8	534.7
Other assets	305.6	245.4
Total assets	5,491	5,501.8
Current Liabilities:
Accounts payable	455.3	498.8
Accrued liabilities	220.4	260.1
Short-term contract liabilities	77.9	71.4
Short-term debt and current portion of long-term debt	6.4	6.6
Total current liabilities	760	836.9
Long-term debt	1,536.2	1,535.5
Accrued postretirement benefits	309.5	318.4
Pension liabilities	701.1	730
Deferred income taxes	14.5	12.9
Other long-term liabilities	123.1	76.5
Total liabilities	3,444.4	3,510.2
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-126,695,171 shares at March 31, 2019 and December 31, 2018; outstanding-126,034,880 shares at March 31, 2019 and 125,684,396 shares at December 31, 2018	12.7	12.7
Additional paid-in capital	1,599.7	1,615.4
Retained earnings	1,437	1,422
Treasury stock: 660,291 shares at March 31, 2019 and 1,010,775 shares at December 31, 2018	(19.7)	(30.6)
Accumulated other comprehensive loss, net of tax	(1,095.5)	(1,133.8)
Total ATI stockholders’ equity	1,934.2	1,885.7
Noncontrolling interests
Noncontrolling interests	112.4	105.9
Total Equity	2,046.6	1,991.6
Total Liabilities and Equity	$ 5,491	$ 5,501.8

CONSOLIDATED BALANCE SHEETS (PA

CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
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	126,695,171	126,695,171
Common stock, oustanding	126,034,880	125,684,396
Treasury stock	660,291	1,010,775

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Sales	$ 1,004.8	$ 979
Cost of sales	873.7	830.4
Gross profit	131.1	148.6
Selling and administrative expenses	68	67.1
Operating income	63.1	81.5
Nonoperating retirement benefit expense	(18.3)	(8.3)
Interest expense, net	(24.8)	(25.5)
Other (expense) income, net	(2.9)	17.8
Income before income taxes	17.1	65.5
Income tax provision	0.8	5
Net income (loss)	16.3	60.5
Less: Net income attributable to noncontrolling interests	1.3	2.5
Net income (loss) attributable to ATI	$ 15	$ 58
Basic net income attributable to ATI per common share (in dollars per share)	$ 0.12	$ 0.46
Diluted net income attributable to ATI per common share (in dollars per share)	$ 0.12	$ 0.42

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 16.3	$ 60.5
Currency translation adjustment
Unrealized net change arising during the period	11	23.6
Derivatives
Net derivatives gain on hedge transactions	10.5	3.3
Reclassification to net income of net realized loss (gain)	0.9	(3)
Income taxes on derivative transactions	0	0
Total	11.4	0.3
Postretirement benefit plans
Amortization of net actuarial loss	21.7	19.2
Amortization to net income of net prior service credits	(0.6)	(0.6)
Income taxes on postretirement benefit plans	0	0
Total	21.1	18.6
Other comprehensive income, net of tax	43.5	42.5
Comprehensive income	59.8	103
Less: Comprehensive income attributable to noncontrolling interests	6.5	9.4
Comprehensive income attributable to ATI	$ 53.3	$ 93.6

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Activities:
Net income	$ 16.3	$ 60.5
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	38.7	39.8
Deferred taxes	1.6	(0.2)
Gain on joint venture deconsolidation	0	(15.9)
Changes in operating assets and liabilities:
Inventories	(43.3)	(108.4)
Accounts receivable	(37.3)	(61.7)
Accounts payable	(43.5)	79.8
Retirement benefits	(18.4)	0.5
Accrued income taxes	0.5	2.4
Accrued liabilities and other	(44.6)	(43.9)
Cash used in operating activities	(130)	(47.1)
Investing Activities:
Purchases of property, plant and equipment	(23.5)	(41.6)
Asset disposals and other	(0.1)	0.1
Cash used in investing activities	(23.6)	(41.5)
Financing Activities:
Borrowings on long-term debt	0	6.4
Payments on long-term debt and finance leases	(1.5)	(1.3)
Net borrowings under credit facilities	0	50.9
Sales to noncontrolling interests	0	7.4
Shares repurchased for income tax withholding on share-based compensation and other	(9.9)	(6.5)
Cash (used in) provided by financing activities	(11.4)	56.9
Increase (decrease) in cash and cash equivalents
Decrease in cash and cash equivalents	(165)	(31.7)
Cash and cash equivalents at beginning of period	382	141.6
Cash and cash equivalents at end of period	$ 217	$ 109.9

STATEMENTS OF CHANGES IN CONSOL

STATEMENTS OF CHANGES IN CONSOLIDATED EQUITY - USD ($) $ in Millions	Total	[CommonStockMember]	[AdditionalPaidInCapitalMember]	[RetainedEarningsMember]	[TreasuryStockMember]	[AccumulatedOtherComprehensiveIncomeMember]	[NoncontrollingInterestMember]
Total Stockholders' Equity at Dec. 31, 2017	$ 1,844.5	$ 12.7	$ 1,596.3	$ 1,184.3	$ (26.1)	$ (1,027.8)	$ 105.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	60.5			58			2.5
Other comprehensive income	42.5					35.6	6.9
Cumulative effect of adoption of new accounting standard	15.5			15.5
Sales of subsidiary shares to noncontrolling interest	2.7						2.7
Employee stock plans	(2.4)		3.2	0	(5.6)
Total Stockholders' Equity at Mar. 31, 2018	1,963.3	12.7	1,599.5	1,257.8	(31.7)	(992.2)	117.2
Total Stockholders' Equity at Dec. 31, 2018	1,991.6	12.7	1,615.4	1,422	(30.6)	(1,133.8)	105.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16.3			15			1.3
Other comprehensive income	43.5					38.3	5.2
Employee stock plans	(4.8)		(15.7)	0	10.9
Total Stockholders' Equity at Mar. 31, 2019	$ 2,046.6	$ 12.7	$ 1,599.7	$ 1,437	$ (19.7)	$ (1,095.5)	$ 112.4

Accounting Policies

Accounting Policies	3 Months Ended
	Mar. 31, 2019
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 fiscal year 2019 presentation. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2018 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, 2018 financial information has been derived from the Company’s audited consolidated financial statements. New Accounting Pronouncements Adopted In January 2019, the Company adopted changes issued by the Financial Accounting Standards Board (FASB) related to leases. See Note 7 for further explanation related to this adoption, including all newly expanded disclosure requirements. Pending Accounting Pronouncements In August 2018, the FASB issued new disclosure guidance on fair value measurement. This new guidance modifies the disclosure requirements on fair value measurements, including removal and modifications of various current disclosures as well as some additional disclosure requirements for Level 3 fair value measurements. Some of these disclosure changes must be applied prospectively while others retrospectively depending on requirement. This guidance is required to be adopted by the Company beginning in fiscal year 2020 with early adoption permitted. The Company does not plan to early adopt this guidance. The adoption of these changes is not expected to have an impact on the Company’s consolidated financial statements other than disclosures.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers Disaggregation of Revenue The Company operates in two business segments: High Performance Materials & Components (HPMC) and Flat Rolled Products (FRP). Revenue is disaggregated within these two business segments by diversified global markets, primary geographical markets and diversified products. Comparative information of the Company’s overall revenues (in millions) by global and geographical markets for the first quarters ended March 31, 2019 and 2018 were as follows: (in millions) First quarter ended March 31, 2019 March 31, 2018 HPMC FRP Total HPMC FRP Total Diversified Global Markets: Aerospace & Defense $ 465.1 $ 60.5 $ 525.6 $ 426.7 $ 35.7 $ 462.4 Oil & Gas 16.7 96.1 112.8 15.2 137.5 152.7 Automotive 3.6 73.3 76.9 2.6 76.5 79.1 Construction/Mining 18.5 39.4 57.9 17.6 38.0 55.6 Electrical Energy 27.3 28.4 55.7 30.8 21.4 52.2 Food Equipment & Appliances 0.1 53.1 53.2 0.1 58.8 58.9 Medical 42.7 3.4 46.1 41.2 3.7 44.9 Electronics/Computers/Communications 1.1 33.0 34.1 1.5 31.4 32.9 Other 26.1 16.4 42.5 25.0 15.3 40.3 Total $ 601.2 $ 403.6 $ 1,004.8 $ 560.7 $ 418.3 $ 979.0 (in millions) First quarter ended March 31, 2019 March 31, 2018 HPMC FRP Total HPMC FRP Total Primary Geographical Market: United States $ 336.0 $ 285.1 $ 621.1 $ 289.8 $ 264.5 $ 554.3 Europe 178.3 32.7 211.0 197.0 28.5 225.5 Asia 52.8 70.4 123.2 48.3 102.5 150.8 Canada 19.1 7.3 26.4 16.6 10.6 27.2 South America, Middle East and other 15.0 8.1 23.1 9.0 12.2 21.2 Total $ 601.2 $ 403.6 $ 1,004.8 $ 560.7 $ 418.3 $ 979.0 Comparative information of the Company’s major high-value and standard products based on their percentages of sales is included in the following table. FRP conversion services are excluded from this presentation. First quarter ended March 31, 2019 March 31, 2018 HPMC FRP Total HPMC FRP Total Diversified Products and Services: High-Value Products Nickel-based alloys and specialty alloys 31 % 29 % 30 % 29 % 31 % 30 % Precision forgings, castings and components 32 % — % 19 % 38 % — % 21 % Titanium and titanium-based alloys 27 % 6 % 19 % 24 % 5 % 16 % Precision and engineered strip — % 33 % 13 % — % 31 % 14 % Zirconium and related alloys 10 % — % 6 % 9 % — % 5 % Total High-Value Products 100 % 68 % 87 % 100 % 67 % 86 % Standard Products Stainless steel sheet — % 17 % 7 % — % 20 % 8 % Specialty stainless sheet — % 11 % 4 % — % 9 % 4 % Stainless steel plate and other — % 4 % 2 % — % 4 % 2 % Total Standard Products — % 32 % 13 % — % 33 % 14 % Total 100 % 100 % 100 % 100 % 100 % 100 % The Company maintains a backlog of confirmed orders totaling $2.59 billion and $2.05 billion at March 31, 2019 and 2018 , respectively. Due to the structure of the Company’s long-term agreements, approximately 80% of this backlog at March 31, 2019 represented booked orders with performance obligations that will be satisfied within the next 12 months. The backlog does not reflect any elements of variable consideration. Contract balances As of March 31, 2019 and December 31, 2018 , accounts receivable with customers were $570.8 million and $533.8 million , respectively. The following represents the rollforward of accounts receivable - reserve for doubtful accounts and contract assets and liabilities for the three months ended March 31, 2019 and 2018 : (in millions) Accounts Receivable - Reserve for Doubtful Accounts March 31, March 31, Balance as of beginning of fiscal year $ 6.0 $ 5.9 Expense to increase the reserve 0.1 0.3 Write-off of uncollectible accounts (0.4 ) (0.3 ) Balance as of period end $ 5.7 $ 5.9 (in millions) Contract Assets Short-term March 31, March 31, Balance as of beginning of fiscal year $ 51.2 $ 36.5 Recognized in current year 23.9 23.4 Reclassified to accounts receivable (26.4 ) (22.1 ) Impairment — — Reclassification to/from long-term — 0.8 Balance as of period end $ 48.7 $ 38.6 Long-term March 31, March 31, Balance as of beginning of fiscal year $ 0.1 $ 16.9 Recognized in current year — — Reclassified to accounts receivable — — Impairment — — Reclassification to/from short-term — (0.8 ) Balance as of period end $ 0.1 $ 16.1 (in millions) Contract Liabilities Short-term March 31, March 31, Balance as of beginning of fiscal year $ 71.4 $ 69.7 Recognized in current year 38.6 8.4 Amounts in beginning balance reclassified to revenue (29.3 ) (14.1 ) Current year amounts reclassified to revenue (2.8 ) (0.3 ) Other — — Reclassification to/from long-term — 2.5 Balance as of period end $ 77.9 $ 66.2 Long-term March 31, March 31, Balance as of beginning of fiscal year $ 7.3 $ 22.2 Recognized in current year 0.3 0.2 Amounts in beginning balance reclassified to revenue (0.3 ) (0.2 ) Current year amounts reclassified to revenue — — Other — — Reclassification to/from short-term — (2.5 ) Balance as of period end $ 7.3 $ 19.7 Contract costs for obtaining and fulfilling a contract were $5.2 million as of both March 31, 2019 and December 31, 2018 , and are reported in other long-term assets on the consolidated balance sheet. Amortization expense for both the three months ended March 31, 2019 and 2018 of these contract costs was $0.3 million .

Inventories

Inventories	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories at March 31, 2019 and December 31, 2018 were as follows (in millions): March 31, December 31, Raw materials and supplies $ 212.5 $ 191.5 Work-in-process 941.3 914.1 Finished goods 192.4 191.1 Total inventories at current cost 1,346.2 1,296.7 Adjustment from current cost to LIFO cost basis 4.7 2.9 Inventory valuation reserves (96.5 ) (88.5 ) Total inventories, net $ 1,254.4 $ 1,211.1 Inventories are stated at the lower of cost (last-in, first-out (LIFO), first-in, first-out (FIFO), and average cost methods) or market. 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. Due to deflationary impacts primarily related to raw materials, the carrying value of the Company’s inventory as valued on LIFO exceeds current replacement cost, and based on a lower of cost or market value analysis, the Company maintains NRV inventory valuation reserves to adjust carrying value of LIFO inventory to current replacement cost. These NRV reserves were $9.9 million at March 31, 2019 and $8.0 million at December 31, 2018 . Impacts to cost of sales for changes in the LIFO costing methodology and associated NRV inventory reserves were as follows (in millions): Three months ended March 31, 2019 2018 LIFO benefit (charge) $ 1.8 $ (8.2 ) NRV benefit (charge) (1.9 ) 8.2 Net cost of sales impact $ (0.1 ) $ —

Property Plant And Equipment

Property Plant And Equipment	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Property Plant and Equipment	Property, Plant and Equipment Property, plant and equipment at March 31, 2019 and December 31, 2018 was as follows (in millions): March 31, December 31, Land $ 31.6 $ 31.5 Buildings 853.9 851.7 Equipment and leasehold improvements 3,653.0 3,622.7 4,538.5 4,505.9 Accumulated depreciation and amortization (2,067.8 ) (2,030.9 ) Total property, plant and equipment, net $ 2,470.7 $ 2,475.0 The construction in progress portion of property, plant and equipment at March 31, 2019 was $91.3 million .

Joint Ventures

Joint Ventures	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Joint Ventures	Joint Ventures The financial results of majority-owned joint ventures are consolidated into the Company’s operating results and financial position, with the minority ownership interest recognized in the consolidated statement of income as net income attributable to noncontrolling interests, and as equity attributable to the noncontrolling interests within total stockholders’ equity. Investments in which the Company exercises significant influence, but which it does not control (generally a 20% to 50% ownership interest), are accounted for under the equity method of accounting. Majority-Owned Joint Ventures The Company has a 60% interest in the Chinese joint venture known as Shanghai STAL Precision Stainless Steel Company Limited (STAL). The remaining 40% interest in STAL is owned by China Baowu Steel Group Corporation Limited, a state authorized investment company whose equity securities are publicly traded in the People’s Republic of China. STAL is part of ATI’s Flat Rolled Products segment, and manufactures Precision Rolled Strip stainless products mainly for the electronics, communication equipment, computer and automotive markets located in Asia. Cash and cash equivalents held by STAL as of March 31, 2019 were $39.4 million . The Company has a 51% interest in Next Gen Alloys LLC, a joint venture with GE Aviation for the development of a new meltless titanium alloy powder manufacturing technology. The titanium alloy powders are being developed for use in additive manufacturing applications, including 3D printing. Cash and cash equivalents held by this joint venture as of March 31, 2019 were $9.0 million . During the first quarter 2018, the Company received $2.7 million for the sale of noncontrolling interest related to Next Gen Alloys LLC, which is reported as a financing activity on the consolidated statements of cash flows. Equity Method Joint Ventures On March 1, 2018, the Company announced the formation of the Allegheny & Tsingshan Stainless (A&T Stainless) joint venture with an affiliate company of Tsingshan Group (Tsingshan) to produce 60-inch wide stainless sheet products for sale in North America. Tsingshan purchased a 50% joint venture interest in A&T Stainless for $17.5 million , of which $12.0 million was received in 2018, with $5.0 million received in the first quarter of 2018 and reported as a financing activity on the consolidated statements of cash flows. The A&T Stainless operations include the Company’s previously-idled direct roll and pickle (DRAP) facility in Midland, PA. ATI provides hot-rolling conversion services to A&T Stainless using the FRP segment’s Hot-Rolling and Processing Facility. As a result of this sale of a 50% noncontrolling interest and the subsequent deconsolidation of the A&T Stainless entity, the Company recognized a $15.9 million gain during the first quarter of 2018 under deconsolidation and derecognition accounting guidance covering the loss of control of a subsidiary determined to be a business. The gain, including ATI’s retained 50% share, was based on the fair value of the joint venture, as determined by the cash purchase price for the noncontrolling interest, and is reported in other (expense) income, net on the consolidated statement of income, and is excluded from FRP segment results. Following this deconsolidation, ATI accounts for the A&T Stainless joint venture under the equity method of accounting. As of March 31, 2019, ATI’s equity method investment in the A&T Stainless joint venture was $7.8 million . ATI’s share of the A&T Stainless joint venture results were losses of $3.3 million and $0.6 million for the three months ended March 31, 2019 and 2018, respectively, which is included in the FRP segment’s operating results, and within other (expense) income, net, on the consolidated statements of income. In late March 2018, ATI filed for an exclusion from the recently enacted Section 232 tariffs on behalf of the A&T Stainless joint venture, which imports semi-finished stainless slab products from Indonesia. On April 24, 2019, the Company learned that this exclusion request had been denied by the U.S. Department of Commerce. Therefore, the joint venture will continue to be subject to the 25% tariff levied on its imports of semi-finished stainless slab products from Indonesia. Results of A&T Stainless have been and will continue to be negatively impacted by these tariffs. ATI has a 50% interest in the industrial titanium joint venture known as Uniti LLC (Uniti), with the remaining 50% interest held by VSMPO, a Russian producer of titanium, aluminum, and specialty steel products. Uniti is accounted for under the equity method of accounting. ATI’s share of Uniti’s income was $0.5 million for both the three months ended March 31, 2019 and 2018, which is included in the FRP segment’s operating results, and within other (expense) income, net on the consolidated statements of income.

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt	Debt Debt at March 31, 2019 and December 31, 2018 was as follows (in millions): March 31, December 31, Allegheny Technologies 5.875% Notes due 2023 (a) $ 500.0 $ 500.0 Allegheny Technologies 5.95% Notes due 2021 500.0 500.0 Allegheny Technologies 4.75% Convertible Senior Notes due 2022 287.5 287.5 Allegheny Ludlum 6.95% Debentures due 2025 150.0 150.0 Term Loan due 2022 100.0 100.0 U.S. revolving credit facility — — Foreign credit facilities — — Other 14.8 15.0 Debt issuance costs (9.7 ) (10.4 ) Total debt 1,542.6 1,542.1 Short-term debt and current portion of long-term debt 6.4 6.6 Total long-term debt $ 1,536.2 $ 1,535.5 (a) Bearing interest at 7.875% effective February 15, 2016. Revolving Credit Facility The Company has a $500 million Asset Based Lending (ABL) Credit Facility, which is collateralized by the accounts receivable and inventory of the Company’s domestic operations. The ABL facility, which matures in February 2022, includes a $400 million revolving credit facility, a letter of credit sub-facility of up to $200 million , and a $100 million term loan (Term Loan). The Term Loan has an interest rate of 2.5% plus a LIBOR spread and can be prepaid in increments of $50 million if certain minimum liquidity conditions are satisfied. The Company has a $50 million floating-for-fixed interest rate swap which converts half of the Term Loan to a 5.44% fixed interest rate. The swap matures in January 2021. The applicable interest rate for revolving credit borrowings under the ABL facility includes interest rate spreads based on available borrowing capacity that range between 1.75% and 2.25% for LIBOR-based borrowings and between 1.0% and 1.5% for base rate borrowings. The ABL facility contains a financial covenant whereby the Company must maintain a fixed charge coverage ratio of not less than 1.00 : 1.00 after an event of default has occurred and is continuing or if the undrawn availability under the ABL revolving credit portion of the facility is less than the greater of (i) 10% of the then applicable maximum borrowing amount under the revolving credit portion of the ABL and any outstanding Term Loan balance, or (ii) $40.0 million . The Company was in compliance with the fixed charge coverage ratio covenant at March 31, 2019 . Additionally, the Company must demonstrate liquidity, as calculated in accordance with the terms of the ABL facility, of at least $700 million on the date that is 91 days prior to January 15, 2021, the maturity date of the 5.95% Senior Notes due 2021, and that such liquidity is available at all times thereafter until the 5.95% Senior Notes due 2021 are paid in full or refinanced. As of March 31, 2019 , there were no outstanding borrowings under the revolving portion of the ABL facility, and $35.3 million was utilized to support the issuance of letters of credit. There were no average revolving credit borrowings under the ABL facility for the first quarter of 2019, and average borrowings of $53 million , bearing an average annual interest rate of 3.50% , for the first quarter of 2018.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases On January 1, 2019 the Company adopted Accounting Standards Codification Topic 842 (ASC 842), Leases. This new guidance requires a lessee to recognize assets and liabilities on the balance sheet for all leases, with the result being the recognition of a right of use (ROU) asset and a lease liability. The lease liability is equal to the present value of the minimum lease payments for the term of the lease, including any optional renewal periods determined to be reasonably certain to be exercised, using the discount rate determined at lease commencement. This discount rate is the rate implicit in the lease, if known; otherwise, the incremental borrowing rate (IBR) for the expected lease term is used. The Company’s IBRs approximate the rate the Company would have to pay to borrow on a collateralized basis over a similar term at lease inception. The ROU asset is equal to the initial measurement of the lease liability plus any lease payments made to the lessor at or before the commencement date and any unamortized initial direct costs incurred by the lessee, less any unamortized lease incentives received. The Company has lease contracts for real property and machinery and equipment, primarily for mobile, office and information technology equipment. At inception of a contract, the Company determines whether the contract is or contains a lease. If the Company has a right to obtain substantially all of the economic benefits from the use of the identified asset and the right to direct the use of the asset, then the contract contains a lease. Several of the Company’s real property lease contracts include options to extend the lease term; however, the Company currently has not included the renewal options for these leases in the ROU asset and lease liability because the likelihood of renewal was not determined to be reasonably certain. The Company will reassess the likelihood of renewal on at least an annual basis. In addition, several real property leases include variable lease payments, for items such as common area maintenance and utilities, which are expensed as incurred as variable lease expense. There are two types of leases, operating leases and finance leases. Lease classification is determined at lease commencement. The criteria used for a lease to be classified as a finance lease is generally consistent with the criteria under the previous lease accounting guidance, ASC 840, for capital leases. All other leases not meeting the finance lease criteria are classified as operating leases. Operating lease expense is recognized on a straight-line basis on the consolidated statement of income. Finance leases have front-loaded expense recognition which is reported as amortization expense and interest expense on the consolidated statement of income. ROU assets for operating leases are classified in other long-term assets, and ROU assets for finance leases are classified in property, plant and equipment on the consolidated balance sheet. For operating leases, short-term lease liabilities are classified in accrued liabilities, and long-term lease liabilities are classified in other long-term liabilities on the consolidated balance sheet. For finance leases, short-term lease liabilities are classified in short-term debt, and long-term lease liabilities are classified in long-term debt on the consolidated balance sheet. On the cash flow statement, payments for operating leases are classified as operating activities. Payments for finance leases are classified as a financing activity, with the exception of the interest component of the payment which is classified as an operating activity. Adoption Method and Impact The Company applied ASC 842 to all leases in effect at January 1, 2019 and adopted the accounting standard using the alternative transition method, which does not require the restatement of prior years. Comparative information has not been adjusted and continues to be reported under the previous accounting guidance. The Company has elected the package of practical expedients, which allows entities to not reassess (1) whether contracts are or contain leases, (2) lease classification and (3) initial direct costs. The Company has also elected the practical expedient to not separate lease components from non-lease components for all asset classes, and did not elect the hindsight practical expedient to determine the lease term. The Company has made an accounting policy election to apply the short-term exception, which does not require the capitalization of leases with terms of 12 months or less. On January 1, 2019, the Company recognized $51.7 million of ROU assets and $55.6 million of lease liabilities ( $12.5 million short-term and $43.1 million long-term) on the consolidated balance sheet for operating leases, with the difference due to deferred rent balances as of December 31, 2018 that reduced the ROU asset balance on January 1, 2019. The adoption did not have a material impact on the Company’s results of operations or cash flows, and had no impact to the net deferred tax position on the consolidated balance sheet due to the Company’s income tax valuation allowances for federal and state purposes (see Note 11). The Company has entered into finance lease contracts with lenders for progress payments on machinery and equipment that is being constructed at the request and specification of the Company. As of March 31, 2019, the lenders had made $1.7 million of progress payments on behalf of the Company, and $5.8 million of progress payments are scheduled to be paid. Upon payment of the final progress payments by the lenders, finance leases will commence, and $7.5 million , discounted using the applicable discount rates at lease inceptions, of ROU assets and lease liabilities will be recognized by the Company. The following represents the components of lease cost and other information for both operating and financing leases for the three months ending March 31, 2019 : ($ in millions) Three months ended March 31, 2019 Lease Cost Finance Lease Cost: Amortization of right of use asset $ 0.2 Interest on lease liabilities 0.1 Operating lease cost 5.1 Short-term lease cost 0.9 Variable lease cost 0.1 Sublease income — Total lease cost $ 6.4 Other information Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from finance leases $ 0.1 Operating cash flows from operating leases $ 5.1 Financing cash flows from finance leases $ 0.3 Right of use assets obtained in exchange for new finance lease liabilities $ 3.6 Right of use assets obtained in exchange for new operating lease liabilities $ 12.4 Weighted average remaining lease term - finance leases 4.22 years Weighted average remaining lease term - operating leases 5.88 years Weighted average discount rate - finance leases 6.3 % Weighted average discount rate - operating leases 7.4 % The following table reconciles future minimum undiscounted rental commitments for operating leases to the operating lease liabilities recorded on the consolidated balance sheet as of March 31, 2019 (in millions): March 31, 2019 Remainder of 2019 $ 14.4 2020 16.3 2021 14.6 2022 11.7 2023 8.2 2024 and Thereafter 18.9 Total undiscounted lease payments $ 84.1 Present value adjustment (17.1 ) Operating lease liabilities $ 67.0 The following table reconciles future minimum undiscounted rental commitments for finance leases to the finance lease liabilities recorded on the consolidated balance sheet as of March 31, 2019 (in millions): March 31, 2019 Remainder of 2019 $ 1.4 2020 1.8 2021 1.6 2022 1.2 2023 1.0 2024 and Thereafter 0.1 Total undiscounted lease payments $ 7.1 Present value adjustment (0.4 ) Finance lease liabilities $ 6.7
Leases	Leases On January 1, 2019 the Company adopted Accounting Standards Codification Topic 842 (ASC 842), Leases. This new guidance requires a lessee to recognize assets and liabilities on the balance sheet for all leases, with the result being the recognition of a right of use (ROU) asset and a lease liability. The lease liability is equal to the present value of the minimum lease payments for the term of the lease, including any optional renewal periods determined to be reasonably certain to be exercised, using the discount rate determined at lease commencement. This discount rate is the rate implicit in the lease, if known; otherwise, the incremental borrowing rate (IBR) for the expected lease term is used. The Company’s IBRs approximate the rate the Company would have to pay to borrow on a collateralized basis over a similar term at lease inception. The ROU asset is equal to the initial measurement of the lease liability plus any lease payments made to the lessor at or before the commencement date and any unamortized initial direct costs incurred by the lessee, less any unamortized lease incentives received. The Company has lease contracts for real property and machinery and equipment, primarily for mobile, office and information technology equipment. At inception of a contract, the Company determines whether the contract is or contains a lease. If the Company has a right to obtain substantially all of the economic benefits from the use of the identified asset and the right to direct the use of the asset, then the contract contains a lease. Several of the Company’s real property lease contracts include options to extend the lease term; however, the Company currently has not included the renewal options for these leases in the ROU asset and lease liability because the likelihood of renewal was not determined to be reasonably certain. The Company will reassess the likelihood of renewal on at least an annual basis. In addition, several real property leases include variable lease payments, for items such as common area maintenance and utilities, which are expensed as incurred as variable lease expense. There are two types of leases, operating leases and finance leases. Lease classification is determined at lease commencement. The criteria used for a lease to be classified as a finance lease is generally consistent with the criteria under the previous lease accounting guidance, ASC 840, for capital leases. All other leases not meeting the finance lease criteria are classified as operating leases. Operating lease expense is recognized on a straight-line basis on the consolidated statement of income. Finance leases have front-loaded expense recognition which is reported as amortization expense and interest expense on the consolidated statement of income. ROU assets for operating leases are classified in other long-term assets, and ROU assets for finance leases are classified in property, plant and equipment on the consolidated balance sheet. For operating leases, short-term lease liabilities are classified in accrued liabilities, and long-term lease liabilities are classified in other long-term liabilities on the consolidated balance sheet. For finance leases, short-term lease liabilities are classified in short-term debt, and long-term lease liabilities are classified in long-term debt on the consolidated balance sheet. On the cash flow statement, payments for operating leases are classified as operating activities. Payments for finance leases are classified as a financing activity, with the exception of the interest component of the payment which is classified as an operating activity. Adoption Method and Impact The Company applied ASC 842 to all leases in effect at January 1, 2019 and adopted the accounting standard using the alternative transition method, which does not require the restatement of prior years. Comparative information has not been adjusted and continues to be reported under the previous accounting guidance. The Company has elected the package of practical expedients, which allows entities to not reassess (1) whether contracts are or contain leases, (2) lease classification and (3) initial direct costs. The Company has also elected the practical expedient to not separate lease components from non-lease components for all asset classes, and did not elect the hindsight practical expedient to determine the lease term. The Company has made an accounting policy election to apply the short-term exception, which does not require the capitalization of leases with terms of 12 months or less. On January 1, 2019, the Company recognized $51.7 million of ROU assets and $55.6 million of lease liabilities ( $12.5 million short-term and $43.1 million long-term) on the consolidated balance sheet for operating leases, with the difference due to deferred rent balances as of December 31, 2018 that reduced the ROU asset balance on January 1, 2019. The adoption did not have a material impact on the Company’s results of operations or cash flows, and had no impact to the net deferred tax position on the consolidated balance sheet due to the Company’s income tax valuation allowances for federal and state purposes (see Note 11). The Company has entered into finance lease contracts with lenders for progress payments on machinery and equipment that is being constructed at the request and specification of the Company. As of March 31, 2019, the lenders had made $1.7 million of progress payments on behalf of the Company, and $5.8 million of progress payments are scheduled to be paid. Upon payment of the final progress payments by the lenders, finance leases will commence, and $7.5 million , discounted using the applicable discount rates at lease inceptions, of ROU assets and lease liabilities will be recognized by the Company. The following represents the components of lease cost and other information for both operating and financing leases for the three months ending March 31, 2019 : ($ in millions) Three months ended March 31, 2019 Lease Cost Finance Lease Cost: Amortization of right of use asset $ 0.2 Interest on lease liabilities 0.1 Operating lease cost 5.1 Short-term lease cost 0.9 Variable lease cost 0.1 Sublease income — Total lease cost $ 6.4 Other information Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from finance leases $ 0.1 Operating cash flows from operating leases $ 5.1 Financing cash flows from finance leases $ 0.3 Right of use assets obtained in exchange for new finance lease liabilities $ 3.6 Right of use assets obtained in exchange for new operating lease liabilities $ 12.4 Weighted average remaining lease term - finance leases 4.22 years Weighted average remaining lease term - operating leases 5.88 years Weighted average discount rate - finance leases 6.3 % Weighted average discount rate - operating leases 7.4 % The following table reconciles future minimum undiscounted rental commitments for operating leases to the operating lease liabilities recorded on the consolidated balance sheet as of March 31, 2019 (in millions): March 31, 2019 Remainder of 2019 $ 14.4 2020 16.3 2021 14.6 2022 11.7 2023 8.2 2024 and Thereafter 18.9 Total undiscounted lease payments $ 84.1 Present value adjustment (17.1 ) Operating lease liabilities $ 67.0 The following table reconciles future minimum undiscounted rental commitments for finance leases to the finance lease liabilities recorded on the consolidated balance sheet as of March 31, 2019 (in millions): March 31, 2019 Remainder of 2019 $ 1.4 2020 1.8 2021 1.6 2022 1.2 2023 1.0 2024 and Thereafter 0.1 Total undiscounted lease payments $ 7.1 Present value adjustment (0.4 ) Finance lease liabilities $ 6.7

Derivative Financial Instrument

Derivative Financial Instruments and Hedging	3 Months Ended
	Mar. 31, 2019
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. 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 March 31, 2019 , 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 14 million pounds of nickel with hedge dates through 2023. The aggregate notional amount hedged is approximately 14% of a single year’s estimated nickel raw material purchase requirements. At March 31, 2019 , the outstanding financial derivatives used to hedge the Company’s exposure to energy cost volatility included natural gas cost hedges. At March 31, 2019 , the Company hedged approximately 55% of the Company’s forecasted domestic requirements for natural gas for the remainder of 2019 and approximately 40% for 2020. 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, primarily euro. In addition, the Company may also designate cash balances held in foreign currencies as hedges of forecasted foreign currency transactions. At March 31, 2019 , the Company held euro forward sales contracts designated as cash flow hedges with a notional value of approximately 33 million euro with maturity dates through December 2019. The Company may enter into derivative interest rate contracts to maintain a reasonable balance between fixed- and floating-rate debt. The Company has a $50 million floating-for-fixed interest rate swap which converts half of the Term Loan to a 5.44% fixed interest rate. The Company designated the interest rate swap as a cash flow hedge of the Company’s exposure to the variability of the payment of interest on a portion of its Term Loan borrowings. The swap matures in January 2021. 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) Asset derivatives Balance sheet location March 31, December 31, Derivatives designated as hedging instruments: Foreign exchange contracts Prepaid expenses and other current assets $ 0.3 $ — Natural gas contacts Prepaid expenses and other current assets 0.3 0.8 Nickel and other raw material contracts Prepaid expenses and other current assets 4.6 1.2 Natural gas contracts Other assets — 0.2 Nickel and other raw material contracts Other assets 2.4 0.8 Total derivatives designated as hedging instruments 7.6 3.0 Derivatives not designated as hedging instruments: Foreign exchange contracts Prepaid expenses and other current assets 0.5 0.4 Total derivatives not designated as hedging instruments 0.5 0.4 Total asset derivatives $ 8.1 $ 3.4 Liability derivatives Balance sheet location Derivatives designated as hedging instruments: Interest rate swap Accrued liabilities $ 0.3 $ 0.2 Foreign exchange contracts Accrued liabilities — 0.6 Natural gas contracts Accrued liabilities 0.1 0.1 Nickel and other raw material contracts Accrued liabilities 1.9 6.8 Interest rate swap Other long-term liabilities 0.3 0.3 Natural gas contracts Other long-term liabilities 0.2 0.3 Nickel and other raw material contracts Other long-term liabilities 0.5 2.1 Total derivatives designated as hedging instruments 3.3 10.4 Total liability derivatives $ 3.3 $ 10.4 For derivative financial instruments that are designated as cash flow hedges, 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. For derivative financial instruments that are designated as fair value hedges, changes in the fair value of these derivatives are recognized in current period results and are reported as changes within accrued liabilities and other on the consolidated statements of cash flows. There were no outstanding fair value hedges as of March 31, 2019 . The Company did not use net investment hedges for the periods presented. The effects of derivative instruments in the tables below are presented net of related income taxes, excluding any impacts of changes to income tax valuation allowances effecting results of operations or other comprehensive income, when applicable (see Note 15 for further explanation). Assuming market prices remain constant with those at March 31, 2019 , a pre-tax gain of $2.9 million is expected to be recognized over the next 12 months. Activity with regard to derivatives designated as cash flow hedges for the three month periods ended March 31, 2019 and 2018 was as follows (in millions): Amount of Gain (Loss) Recognized in OCI on Derivatives Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (a) Three months ended March 31, Three months ended March 31, Derivatives in Cash Flow Hedging Relationships 2019 2018 2019 2018 Nickel and other raw material contracts $ 8.3 $ 3.1 $ (0.4 ) $ 2.8 Natural gas contracts (0.4 ) 0.2 0.1 (0.3 ) Foreign exchange contracts 0.3 (0.8 ) (0.3 ) (0.2 ) Interest rate swap (0.2 ) — (0.1 ) — Total $ 8.0 $ 2.5 $ (0.7 ) $ 2.3 (a) The gains (losses) reclassified from accumulated OCI into income related to the derivatives, with the exception of the interest rate swap, are presented in cost of sales in the same period or periods in which the hedged item affects earnings. The gains (losses) reclassified from accumulated OCI into income on the interest rate swap are presented in interest expense in the same period as the interest expense on the Term Loan is recognized in earnings. 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. The Company has 7 million euro notional value outstanding as of March 31, 2019 of foreign currency forward contracts not designated as hedges, with maturity dates into the second quarter of 2019. These derivatives that are not designated as hedging instruments were as follows: (In millions) Amount of Gain (Loss) Recognized in Income on Derivatives Three months ended March 31, Derivatives Not Designated as Hedging Instruments 2019 2018 Foreign exchange contracts $ 0.1 $ (0.2 ) Changes in the fair value of foreign exchange contract derivatives not designated as hedging instruments are recorded in cost of sales and are reported as changes within accrued liabilities and other on the consolidated statements of cash flows.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Of Financial Instruments	Fair Value of Financial Instruments The estimated fair value of financial instruments at March 31, 2019 was as follows: Fair Value Measurements at Reporting Date Using (In millions) Total Carrying Amount Total Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Cash and cash equivalents $ 217.0 $ 217.0 $ 217.0 $ — Derivative financial instruments: Assets 8.1 8.1 — 8.1 Liabilities 3.3 3.3 — 3.3 Debt (a) 1,552.3 1,866.6 1,751.8 114.8 The estimated fair value of financial instruments at December 31, 2018 was as follows: Fair Value Measurements at Reporting Date Using (In millions) Total Carrying Amount Total Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Cash and cash equivalents $ 382.0 $ 382.0 $ 382.0 $ — Derivative financial instruments: Assets 3.4 3.4 — 3.4 Liabilities 10.4 10.4 — 10.4 Debt (a) 1,552.5 1,739.4 1,624.4 115.0 (a) The total carrying amount for debt excludes debt issuance costs related to the recognized debt liability which is presented in the consolidated balance sheet as a direct reduction from the carrying amount of the debt liability. 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 availability of observable market data is monitored to assess the appropriate classification of financial instruments within the fair value hierarchy. Changes in economic conditions or model-based valuation techniques may require the transfer of financial instruments from one fair value level to another. In such instances, the transfer is reported at the beginning of the reporting period. No transfers between levels were reported in 2019 or 2018 . 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.

Retirement Benefits

Retirement Benefits	3 Months Ended
	Mar. 31, 2019
Retirement Benefits [Abstract]
Retirement Benefits	The Company has defined contribution retirement plans or defined benefit pension plans covering substantially all employees. Company contributions to defined contribution retirement plans are generally based on a percentage of eligible pay or based on hours worked. 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 (IRC). The Company also sponsors several postretirement plans covering certain collectively-bargained salaried and hourly employees. The plans provide health care and life insurance benefits for eligible retirees. In most retiree health care plans, Company contributions towards premiums are capped based on the cost as of a certain date, thereby creating a defined contribution. For the three month periods ended March 31, 2019 and 2018 , the components of pension and other postretirement benefit expense for the Company’s defined benefit plans included the following (in millions): Pension Benefits Other Postretirement Benefits Three months ended March 31, Three months ended March 31, 2019 2018 2019 2018 Service cost - benefits earned during the year $ 3.2 $ 4.2 $ 0.5 $ 0.6 Interest cost on benefits earned in prior years 26.3 26.1 3.7 3.1 Expected return on plan assets (32.8 ) (39.5 ) — — Amortization of prior service cost (credit) 0.1 0.1 (0.7 ) (0.7 ) Amortization of net actuarial loss 18.4 16.5 3.3 2.7 Total retirement benefit expense $ 15.2 $ 7.4 $ 6.8 $ 5.7

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company maintains income tax valuation allowances on its U.S. Federal and state deferred tax assets based upon the examination of all positive and negative evidence as of the reporting date. Results in both 2019 and 2018 include impacts from income taxes that differ from applicable standard tax rates, primarily related to the income tax valuation allowance. First quarter 2019 and 2018 results included a provision for income taxes of $0.8 million , or 4.7% of income before taxes, and $5.0 million , or 7.6% of income before income taxes, respectively, primarily related to the benefit from the valuation allowances mentioned above and income taxes on non-U.S. operations. The Company continues to analyze the impact of the Tax Cut and Jobs Act as additional guidance is finalized. At this time, the Company has not made any material adjustments to the previously presented amounts in the 2018 and 2017 financial statements.

Business Segments

Business Segments	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Business Segments	Business Segments The Company operates in two business segments: High Performance Materials & Components and Flat Rolled Products. The measure of segment operating profit, which is used to analyze the performance and results of the business segments, excludes all effects of LIFO inventory accounting and any related changes in net realizable value inventory reserves which offset the Company’s aggregate net debit LIFO valuation balance, income taxes, corporate expenses, net interest expense, closed operations and other expenses, restructuring and asset impairment charges, and non-operating gains and losses. 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 March 31, 2019 2018 Total sales: High Performance Materials & Components $ 623.9 $ 579.4 Flat Rolled Products 427.2 439.1 1,051.1 1,018.5 Intersegment sales: High Performance Materials & Components 22.7 18.7 Flat Rolled Products 23.6 20.8 46.3 39.5 Sales to external customers: High Performance Materials & Components 601.2 560.7 Flat Rolled Products 403.6 418.3 $ 1,004.8 $ 979.0 Three months ended March 31, 2019 2018 Operating profit (loss): High Performance Materials & Components $ 72.6 $ 85.5 Flat Rolled Products (10.9 ) 10.9 Total operating profit 61.7 96.4 LIFO and net realizable value reserves (0.1 ) — Corporate expenses (16.6 ) (13.2 ) Closed operations and other expenses (3.1 ) (8.1 ) Gain on joint venture deconsolidation (See Note 5) — 15.9 Interest expense, net (24.8 ) (25.5 ) Income before income taxes $ 17.1 $ 65.5 Closed operations and other expenses were lower in the first quarter of 2019 , compared to the prior year period, primarily from lower carry costs and environmental costs for closed facilities in 2019, along with foreign currency remeasurement gains in 2019 compared to losses in 2018 from the Company’s European Treasury Center. The increase in Corporate expenses in the first quarter 2019, compared to the prior year period, includes higher expense for company-owned life insurance policies and higher incentive compensation costs.

Per Share Information

Per Share Information	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Per Share Information	Per Share Information The following table sets forth the computation of basic and diluted income per common share: Three months ended (In millions, except per share amounts) March 31, 2019 2018 Numerator: Numerator for basic income per common share – Net income attributable to ATI $ 15.0 $ 58.0 Effect of dilutive securities: 4.75% Convertible Senior Notes due 2022 — 3.2 Numerator for diluted income per common share – Net income attributable to ATI after assumed conversions $ 15.0 $ 61.2 Denominator: Denominator for basic net income per common share – weighted average shares 125.4 125.0 Effect of dilutive securities: Share-based compensation 0.7 0.6 4.75% Convertible Senior Notes due 2022 — 19.9 Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions 126.1 145.5 Basic net income attributable to ATI per common share $ 0.12 $ 0.46 Diluted net income attributable to ATI per common share $ 0.12 $ 0.42 Common stock that would be issuable upon the assumed conversion of the 4.75% Convertible Senior Notes due 2022 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 19.9 million anti-dilutive shares for the three months ended March 31, 2019 . There were no anti-dilutive shares for the three months ended March 31, 2018.

Financial Information for Subsi

Financial Information for Subsidiary and Guarantor Parent	3 Months Ended
	Mar. 31, 2019
Condensed Financial Information 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 plans, which cover 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 U.S. qualified defined benefit pension assets or liabilities, or the related deferred taxes and valuation allowances. These 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. The effects of income tax valuation allowances on U.S. Federal and State deferred tax assets are excluded from the Subsidiary’s financial results, and are reported by the Guarantor Parent or the non-guarantor subsidiaries, as applicable. Allegheny Technologies Incorporated Financial Information for Subsidiary and Guarantor Parent Balance Sheets March 31, 2019 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Assets: Cash and cash equivalents $ 0.3 $ 12.5 $ 204.2 $ — $ 217.0 Accounts receivable, net — 157.0 408.1 — 565.1 Intercompany notes receivable — — 4,158.6 (4,158.6 ) — Short-term contract assets — — 48.7 — 48.7 Inventories, net — 250.4 1,004.0 — 1,254.4 Prepaid expenses and other current assets 7.0 47.7 38.0 — 92.7 Total current assets 7.3 467.6 5,861.6 (4,158.6 ) 2,177.9 Property, plant and equipment, net 2.7 1,538.0 930.0 — 2,470.7 Goodwill — — 536.8 — 536.8 Intercompany notes receivable — — 200.0 (200.0 ) — Investment in subsidiaries 6,183.1 37.7 — (6,220.8 ) — Other assets 43.0 54.1 208.5 — 305.6 Total assets $ 6,236.1 $ 2,097.4 $ 7,736.9 $ (10,579.4 ) $ 5,491.0 Liabilities and stockholders’ equity: Accounts payable $ 5.1 $ 174.7 $ 275.5 $ — $ 455.3 Accrued liabilities 27.3 74.8 118.3 — 220.4 Intercompany notes payable 2,186.7 1,971.9 — (4,158.6 ) — Short-term contract liabilities — 50.3 27.6 — 77.9 Short-term debt and current portion of long-term debt 0.4 0.1 5.9 — 6.4 Total current liabilities 2,219.5 2,271.8 427.3 (4,158.6 ) 760.0 Long-term debt 1,280.1 149.7 106.4 — 1,536.2 Intercompany notes payable — 200.0 — (200.0 ) — Accrued postretirement benefits — 255.4 54.1 — 309.5 Pension liabilities 653.4 3.8 43.9 — 701.1 Deferred income taxes 14.5 — — — 14.5 Other long-term liabilities 22.0 36.8 64.3 — 123.1 Total liabilities 4,189.5 2,917.5 696.0 (4,358.6 ) 3,444.4 Total stockholders’ equity (deficit) 2,046.6 (820.1 ) 7,040.9 (6,220.8 ) 2,046.6 Total liabilities and stockholders’ equity $ 6,236.1 $ 2,097.4 $ 7,736.9 $ (10,579.4 ) $ 5,491.0 Allegheny Technologies Incorporated Financial Information for Subsidiary and Guarantor Parent Statements of Income and Comprehensive Income For the three months ended March 31, 2019 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Sales $ — $ 335.5 $ 669.3 $ — $ 1,004.8 Cost of sales 3.2 318.4 552.1 — 873.7 Gross profit (loss) (3.2 ) 17.1 117.2 — 131.1 Selling and administrative expenses 30.4 7.4 30.2 — 68.0 Operating income (loss) (33.6 ) 9.7 87.0 — 63.1 Nonoperating retirement benefit expense (11.7 ) (6.2 ) (0.4 ) — (18.3 ) Interest income (expense), net (37.9 ) (33.9 ) 47.0 — (24.8 ) Other income (loss) including equity in income of unconsolidated subsidiaries 100.3 (2.9 ) (0.4 ) (99.9 ) (2.9 ) Income (loss) before income tax provision (benefit) 17.1 (33.3 ) 133.2 (99.9 ) 17.1 Income tax provision (benefit) 0.8 (8.0 ) 29.9 (21.9 ) 0.8 Net income (loss) 16.3 (25.3 ) 103.3 (78.0 ) 16.3 Less: Net income attributable to noncontrolling interests — — 1.3 — 1.3 Net income (loss) attributable to ATI $ 16.3 $ (25.3 ) $ 102.0 $ (78.0 ) $ 15.0 Comprehensive income (loss) attributable to ATI $ 59.8 $ (22.1 ) $ 107.8 $ (92.2 ) $ 53.3 Condensed Statements of Cash Flows For the three months ended March 31, 2019 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Cash flows provided by (used in) operating activities $ (53.5 ) $ (115.8 ) $ 39.3 $ — $ (130.0 ) Investing Activities: Purchases of property, plant and equipment (0.3 ) (2.4 ) (20.8 ) — (23.5 ) Net receipts/(payments) on intercompany activity — — (184.0 ) 184.0 — Asset disposals and other (0.1 ) — — — (0.1 ) Cash flows provided by (used in) investing activities (0.4 ) (2.4 ) (204.8 ) 184.0 (23.6 ) Financing Activities: Payments on long-term debt and finance leases (0.1 ) — (1.4 ) — (1.5 ) Net receipts/(payments) on intercompany activity 64.1 119.9 — (184.0 ) — Shares repurchased for income tax withholding on share-based compensation and other (9.9 ) — — — (9.9 ) Cash flows provided by (used in) financing activities 54.1 119.9 (1.4 ) (184.0 ) (11.4 ) Increase (decrease) in cash and cash equivalents $ 0.2 $ 1.7 $ (166.9 ) $ — $ (165.0 ) Allegheny Technologies Incorporated Financial Information for Subsidiary and Guarantor Parent Balance Sheets December 31, 2018 Guarantor Non-guarantor (In millions) Parent Subsidiary Subsidiaries Eliminations Consolidated Assets: Cash and cash equivalents $ 0.1 $ 10.8 $ 371.1 $ — $ 382.0 Accounts receivable, net — 126.3 401.5 — 527.8 Intercompany notes receivable — — 3,968.8 (3,968.8 ) — Short-term contract assets — — 51.2 — 51.2 Inventories, net — 216.1 995.0 — 1,211.1 Prepaid expenses and other current assets 12.9 29.3 32.4 — 74.6 Total current assets 13.0 382.5 5,820.0 (3,968.8 ) 2,246.7 Property, plant and equipment, net 1.7 1,548.4 924.9 — 2,475.0 Goodwill — — 534.7 — 534.7 Intercompany notes receivable — — 200.0 (200.0 ) — Investment in subsidiaries 6,096.4 37.7 — (6,134.1 ) — Other assets 35.6 30.7 179.1 — 245.4 Total assets $ 6,146.7 $ 1,999.3 $ 7,658.7 $ (10,302.9 ) $ 5,501.8 Liabilities and stockholders’ equity: Accounts payable $ 3.3 $ 177.5 $ 318.0 $ — $ 498.8 Accrued liabilities 59.1 71.7 129.3 — 260.1 Intercompany notes payable 2,102.8 1,866.0 — (3,968.8 ) — Short-term contract liabilities — 33.0 38.4 — 71.4 Short-term debt and current portion of long-term debt 0.2 0.7 5.7 — 6.6 Total current liabilities 2,165.4 2,148.9 491.4 (3,968.8 ) 836.9 Long-term debt 1,278.8 151.8 104.9 — 1,535.5 Intercompany notes payable — 200.0 — (200.0 ) — Accrued postretirement benefits — 259.2 59.2 — 318.4 Pension liabilities 681.6 4.0 44.4 — 730.0 Deferred income taxes 12.9 — — — 12.9 Other long-term liabilities 16.4 17.6 42.5 — 76.5 Total liabilities 4,155.1 2,781.5 742.4 (4,168.8 ) 3,510.2 Total stockholders’ equity (deficit) 1,991.6 (782.2 ) 6,916.3 (6,134.1 ) 1,991.6 Total liabilities and stockholders’ equity $ 6,146.7 $ 1,999.3 $ 7,658.7 $ (10,302.9 ) $ 5,501.8 Allegheny Technologies Incorporated Financial Information for Subsidiary and Guarantor Parent Statements of Operations and Comprehensive Income For the three months ended March 31, 2018 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Sales $ — $ 346.4 $ 632.6 $ — $ 979.0 Cost of sales 4.1 323.2 503.1 — 830.4 Gross profit (loss) (4.1 ) 23.2 129.5 — 148.6 Selling and administrative expenses 23.7 10.3 33.1 — 67.1 Operating income (loss) (27.8 ) 12.9 96.4 — 81.5 Nonoperating retirement benefit expense (3.1 ) (4.9 ) (0.3 ) — (8.3 ) Interest income (expense), net (33.0 ) (25.7 ) 33.2 — (25.5 ) Other income (loss) including equity in income of unconsolidated subsidiaries 129.4 16.8 0.5 (128.9 ) 17.8 Income (loss) before income tax provision (benefit) 65.5 (0.9 ) 129.8 (128.9 ) 65.5 Income tax provision (benefit) 5.0 0.2 20.2 (20.4 ) 5.0 Net income (loss) 60.5 (1.1 ) 109.6 (108.5 ) 60.5 Less: Net income attributable to noncontrolling interests — — 2.5 — 2.5 Net income (loss) attributable to ATI $ 60.5 $ (1.1 ) $ 107.1 $ (108.5 ) $ 58.0 Comprehensive income (loss) attributable to ATI $ 103.0 $ 1.3 $ 124.0 $ (134.7 ) $ 93.6 Condensed Statements of Cash Flows For the three months ended March 31, 2018 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Cash flows provided by (used in) operating activities $ (51.2 ) $ (36.1 ) $ 40.2 $ — $ (47.1 ) Investing Activities: Purchases of property, plant and equipment (0.4 ) (7.3 ) (33.9 ) — (41.6 ) Net receipts/(payments) on intercompany activity — — (88.1 ) 88.1 — Asset disposals and other — 0.1 — — 0.1 Cash flows provided by (used in) investing activities (0.4 ) (7.2 ) (122.0 ) 88.1 (41.5 ) Financing Activities: Borrowings on long-term debt — — 6.4 — 6.4 Payments on long-term debt and finance leases (0.1 ) (0.1 ) (1.1 ) — (1.3 ) Net borrowings under credit facilities — — 50.9 — 50.9 Net receipts/(payments) on intercompany activity 57.7 30.4 — (88.1 ) — Sale to noncontrolling interests — 4.7 2.7 — 7.4 Shares repurchased for income tax withholding on share-based compensation (6.5 ) — — — (6.5 ) Cash flows provided by (used in) financing activities 51.1 35.0 58.9 (88.1 ) 56.9 Decrease in cash and cash equivalents $ (0.5 ) $ (8.3 ) $ (22.9 ) $ — $ (31.7 )

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 were as follows (in millions): Post- retirement benefit plans Currency translation adjustment Derivatives Deferred Tax Asset Valuation Allowance Total Attributable to ATI: Balance, December 31, 2018 $ (1,005.8 ) $ (73.9 ) $ (4.8 ) $ (49.3 ) $ (1,133.8 ) OCI before reclassifications — 5.8 8.0 — 13.8 Amounts reclassified from AOCI (a) 16.1 (b) — (c) 0.7 (d) 7.7 24.5 Net current-period OCI 16.1 5.8 8.7 7.7 38.3 Balance, March 31, 2019 $ (989.7 ) $ (68.1 ) $ 3.9 $ (41.6 ) $ (1,095.5 ) Attributable to noncontrolling interests: Balance, December 31, 2018 $ — $ 11.1 $ — $ — $ 11.1 OCI before reclassifications — 5.2 — — 5.2 Amounts reclassified from AOCI — (b) — — — — Net current-period OCI — 5.2 — — 5.2 Balance, March 31, 2019 $ — $ 16.3 $ — $ — $ 16.3 (a) Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 10). (b) No amounts were reclassified to earnings. (c) Amounts related to derivatives are included in cost of goods sold or interest expense in the period or periods the hedged item affects earnings (see Note 8). (d) Represents the net change in deferred tax asset valuation allowances on changes in AOCI balances between the balance sheet dates. The changes in AOCI by component, net of tax, for the three month period ended March 31, 2018 were as follows (in millions): Post- retirement benefit plans Currency translation adjustment Derivatives Deferred Tax Asset Valuation Allowance Total Attributable to ATI: Balance, December 31, 2017 $ (954.5 ) $ (53.5 ) $ 9.0 $ (28.8 ) $ (1,027.8 ) OCI before reclassifications — 16.7 2.5 — 19.2 Amounts reclassified from AOCI (a) 14.3 (b) — (c) (2.3 ) 4.4 16.4 Net current-period OCI 14.3 16.7 0.2 4.4 35.6 Balance, March 31, 2018 $ (940.2 ) $ (36.8 ) $ 9.2 $ (24.4 ) $ (992.2 ) Attributable to noncontrolling interests: Balance, December 31, 2017 $ — $ 17.3 $ — $ — $ 17.3 OCI before reclassifications — 6.9 — — 6.9 Amounts reclassified from AOCI — (b) — — — — Net current-period OCI — 6.9 — — $ 6.9 Balance, March 31, 2018 $ — $ 24.2 $ — $ — $ 24.2 (a) Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 10). (b) No amounts were reclassified to earnings. (c) Amounts related to derivatives are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 8). Other comprehensive income (loss) amounts (OCI) reported above by category are net of applicable income tax expense (benefit) for each year presented. Income tax expense (benefit) on OCI items is recorded as a change in a deferred tax asset or liability. Amounts recognized in OCI include the impact of any deferred tax asset valuation allowances, when applicable, resulting from the Company’s three year cumulative loss position. Foreign currency translation adjustments, including those pertaining to noncontrolling interests, are generally not adjusted for income taxes as they relate to indefinite investments in non-U.S. subsidiaries. Reclassifications out of AOCI for the three month periods ended March 31, 2019 and 2018 were as follows: Amount reclassified from AOCI Details about AOCI Components (In millions) Three months ended March 31, 2019 Three months ended March 31, 2018 Affected line item in the statements of income Postretirement benefit plans Prior service credit $ 0.6 $ 0.6 (a) Actuarial losses (21.7 ) (19.2 ) (a) (21.1 ) (18.6 ) (c) Total before tax (5.0 ) (4.3 ) Tax benefit (d) $ (16.1 ) $ (14.3 ) Net of tax Derivatives Nickel and other raw material contracts $ (0.5 ) $ 3.7 (b) Natural gas contracts 0.1 (0.4 ) (b) Foreign exchange contracts (0.4 ) (0.3 ) (b) Interest rate swap (0.1 ) — (b) (0.9 ) 3.0 (c) Total before tax (0.2 ) 0.7 Tax provision (benefit) (d) $ (0.7 ) $ 2.3 Net of tax (a) Amounts are reported in nonoperating retirement benefit expense (see Note 10). (b) Amounts related to derivatives, with the exception of the interest rate swap, are included in cost of goods sold in the period or periods the hedged item affects earnings. Amounts related to the interest rate swap are included in interest expense in the same period as the interest expense on the Term Loan is recognized in earnings (see Note 8). (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 income. (d) These amounts exclude the impact of any deferred tax asset valuation allowances, when applicable.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 , the Company’s reserves for environmental remediation obligations totaled approximately $20 million , of which $8 million was included in other current liabilities. The reserve includes estimated probable future costs of $3 million for federal Superfund and comparable state-managed sites; $16 million for formerly owned or operated sites for which the Company has remediation or indemnification obligations; and $1 million for owned or controlled sites at which Company operations have been discontinued. 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. 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 $15 million . 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. 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, environmental, health and safety matters and occupational disease (including as each relates to alleged asbestos exposure), as well as patent infringement, commercial, government contracting, construction, employment, employee and retiree benefits, taxes, environmental, 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. Allegheny Technologies Incorporated and its subsidiary, ATI Titanium LLC (“ATI Titanium”), are parties to a lawsuit captioned US Magnesium, LLC v. ATI Titanium LLC (Case No. 2:17-cv-00923-DB) and filed in federal district court in Salt Lake City, Utah, pertaining to a Supply and Operating Agreement between US Magnesium LLC (“USM”) and ATI Titanium entered into in 2006 (the “Supply Agreement”). In 2016, ATI Titanium notified USM that it would suspend performance under the Supply Agreement in reliance on certain terms and conditions included in the Supply Agreement. USM subsequently filed a claim challenging ATI Titanium’s right to suspend performance under the Supply Agreement, claiming that such suspension was a material breach of the Supply Agreement and seeking monetary damages, and ATI Titanium filed a counterclaim for breach of contract against USM. In 2018, USM obtained leave of the court to add Allegheny Technologies Incorporated as a separate party defendant, and ATI Titanium filed a motion to dismiss the claim against Allegheny Technologies Incorporated, which the court denied on April 19, 2019. The case is in the early stages of discovery, and while ATI intends to vigorously defend against and pursue these claims, it cannot predict their outcomes at this time.

Accounting Policies (Policies)

Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
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 fiscal year 2019 presentation. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2018 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, 2018 financial information has been derived from the Company’s audited consolidated financial statements.
New Accounting Pronouncements Adopted	New Accounting Pronouncements Adopted In January 2019, the Company adopted changes issued by the Financial Accounting Standards Board (FASB) related to leases. See Note 7 for further explanation related to this adoption, including all newly expanded disclosure requirements.
New Accounting Pronouncements Not Yet Adopted	Pending Accounting Pronouncements In August 2018, the FASB issued new disclosure guidance on fair value measurement. This new guidance modifies the disclosure requirements on fair value measurements, including removal and modifications of various current disclosures as well as some additional disclosure requirements for Level 3 fair value measurements. Some of these disclosure changes must be applied prospectively while others retrospectively depending on requirement. This guidance is required to be adopted by the Company beginning in fiscal year 2020 with early adoption permitted. The Company does not plan to early adopt this guidance. The adoption of these changes is not expected to have an impact on the Company’s consolidated financial statements other than disclosures.
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. 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. Due to deflationary impacts primarily related to raw materials, the carrying value of the Company’s inventory as valued on LIFO exceeds current replacement cost, and based on a lower of cost or market value analysis, the Company maintains NRV inventory valuation reserves to adjust carrying value of LIFO inventory to current replacement cost.
Leases	On January 1, 2019 the Company adopted Accounting Standards Codification Topic 842 (ASC 842), Leases. This new guidance requires a lessee to recognize assets and liabilities on the balance sheet for all leases, with the result being the recognition of a right of use (ROU) asset and a lease liability. The lease liability is equal to the present value of the minimum lease payments for the term of the lease, including any optional renewal periods determined to be reasonably certain to be exercised, using the discount rate determined at lease commencement. This discount rate is the rate implicit in the lease, if known; otherwise, the incremental borrowing rate (IBR) for the expected lease term is used. The Company’s IBRs approximate the rate the Company would have to pay to borrow on a collateralized basis over a similar term at lease inception. The ROU asset is equal to the initial measurement of the lease liability plus any lease payments made to the lessor at or before the commencement date and any unamortized initial direct costs incurred by the lessee, less any unamortized lease incentives received. The Company has lease contracts for real property and machinery and equipment, primarily for mobile, office and information technology equipment. At inception of a contract, the Company determines whether the contract is or contains a lease. If the Company has a right to obtain substantially all of the economic benefits from the use of the identified asset and the right to direct the use of the asset, then the contract contains a lease. Several of the Company’s real property lease contracts include options to extend the lease term; however, the Company currently has not included the renewal options for these leases in the ROU asset and lease liability because the likelihood of renewal was not determined to be reasonably certain. The Company will reassess the likelihood of renewal on at least an annual basis. In addition, several real property leases include variable lease payments, for items such as common area maintenance and utilities, which are expensed as incurred as variable lease expense. There are two types of leases, operating leases and finance leases. Lease classification is determined at lease commencement. The criteria used for a lease to be classified as a finance lease is generally consistent with the criteria under the previous lease accounting guidance, ASC 840, for capital leases. All other leases not meeting the finance lease criteria are classified as operating leases. Operating lease expense is recognized on a straight-line basis on the consolidated statement of income. Finance leases have front-loaded expense recognition which is reported as amortization expense and interest expense on the consolidated statement of income. ROU assets for operating leases are classified in other long-term assets, and ROU assets for finance leases are classified in property, plant and equipment on the consolidated balance sheet. For operating leases, short-term lease liabilities are classified in accrued liabilities, and long-term lease liabilities are classified in other long-term liabilities on the consolidated balance sheet. For finance leases, short-term lease liabilities are classified in short-term debt, and long-term lease liabilities are classified in long-term debt on the consolidated balance sheet. On the cash flow statement, payments for operating leases are classified as operating activities. Payments for finance leases are classified as a financing activity, with the exception of the interest component of the payment which is classified as an operating activity.
Derivatives	For derivative financial instruments that are designated as cash flow hedges, 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. For derivative financial instruments that are designated as fair value hedges, changes in the fair value of these derivatives are recognized in current period results and are reported as changes within accrued liabilities and other on the consolidated statements of cash flows. There were no outstanding fair value hedges as of March 31, 2019 . The Company did not use net investment hedges for the periods presented. The effects of derivative instruments in the tables below are presented net of related income taxes, excluding any impacts of changes to income tax valuation allowances effecting results of operations or other comprehensive income, when applicable (see Note 15 for further explanation). 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. 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 March 31, 2019 , 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 14 million pounds of nickel with hedge dates through 2023. The aggregate notional amount hedged is approximately 14% of a single year’s estimated nickel raw material purchase requirements. At March 31, 2019 , the outstanding financial derivatives used to hedge the Company’s exposure to energy cost volatility included natural gas cost hedges. At March 31, 2019 , the Company hedged approximately 55% of the Company’s forecasted domestic requirements for natural gas for the remainder of 2019 and approximately 40% for 2020. 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, primarily euro. In addition, the Company may also designate cash balances held in foreign currencies as hedges of forecasted foreign currency transactions. At March 31, 2019 , the Company held euro forward sales contracts designated as cash flow hedges with a notional value of approximately 33 million euro with maturity dates through December 2019. The Company may enter into derivative interest rate contracts to maintain a reasonable balance between fixed- and floating-rate debt. The Company has a $50 million floating-for-fixed interest rate swap which converts half of the Term Loan to a 5.44% fixed interest rate. The Company designated the interest rate swap as a cash flow hedge of the Company’s exposure to the variability of the payment of interest on a portion of its Term Loan borrowings. The swap matures in January 2021. 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.
Retirement Benefits	The Company has defined contribution retirement plans or defined benefit pension plans covering substantially all employees. Company contributions to defined contribution retirement plans are generally based on a percentage of eligible pay or based on hours worked. 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 (IRC). The Company also sponsors several postretirement plans covering certain collectively-bargained salaried and hourly employees. The plans provide health care and life insurance benefits for eligible retirees. In most retiree health care plans, Company contributions towards premiums are capped based on the cost as of a certain date, thereby creating a defined contribution.
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.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	Comparative information of the Company’s overall revenues (in millions) by global and geographical markets for the first quarters ended March 31, 2019 and 2018 were as follows: (in millions) First quarter ended March 31, 2019 March 31, 2018 HPMC FRP Total HPMC FRP Total Diversified Global Markets: Aerospace & Defense $ 465.1 $ 60.5 $ 525.6 $ 426.7 $ 35.7 $ 462.4 Oil & Gas 16.7 96.1 112.8 15.2 137.5 152.7 Automotive 3.6 73.3 76.9 2.6 76.5 79.1 Construction/Mining 18.5 39.4 57.9 17.6 38.0 55.6 Electrical Energy 27.3 28.4 55.7 30.8 21.4 52.2 Food Equipment & Appliances 0.1 53.1 53.2 0.1 58.8 58.9 Medical 42.7 3.4 46.1 41.2 3.7 44.9 Electronics/Computers/Communications 1.1 33.0 34.1 1.5 31.4 32.9 Other 26.1 16.4 42.5 25.0 15.3 40.3 Total $ 601.2 $ 403.6 $ 1,004.8 $ 560.7 $ 418.3 $ 979.0 (in millions) First quarter ended March 31, 2019 March 31, 2018 HPMC FRP Total HPMC FRP Total Primary Geographical Market: United States $ 336.0 $ 285.1 $ 621.1 $ 289.8 $ 264.5 $ 554.3 Europe 178.3 32.7 211.0 197.0 28.5 225.5 Asia 52.8 70.4 123.2 48.3 102.5 150.8 Canada 19.1 7.3 26.4 16.6 10.6 27.2 South America, Middle East and other 15.0 8.1 23.1 9.0 12.2 21.2 Total $ 601.2 $ 403.6 $ 1,004.8 $ 560.7 $ 418.3 $ 979.0 Comparative information of the Company’s major high-value and standard products based on their percentages of sales is included in the following table. FRP conversion services are excluded from this presentation. First quarter ended March 31, 2019 March 31, 2018 HPMC FRP Total HPMC FRP Total Diversified Products and Services: High-Value Products Nickel-based alloys and specialty alloys 31 % 29 % 30 % 29 % 31 % 30 % Precision forgings, castings and components 32 % — % 19 % 38 % — % 21 % Titanium and titanium-based alloys 27 % 6 % 19 % 24 % 5 % 16 % Precision and engineered strip — % 33 % 13 % — % 31 % 14 % Zirconium and related alloys 10 % — % 6 % 9 % — % 5 % Total High-Value Products 100 % 68 % 87 % 100 % 67 % 86 % Standard Products Stainless steel sheet — % 17 % 7 % — % 20 % 8 % Specialty stainless sheet — % 11 % 4 % — % 9 % 4 % Stainless steel plate and other — % 4 % 2 % — % 4 % 2 % Total Standard Products — % 32 % 13 % — % 33 % 14 % Total 100 % 100 % 100 % 100 % 100 % 100 %
Schedule of Accounts Receivable - Reserve for Doubtful Accounts	(in millions) Accounts Receivable - Reserve for Doubtful Accounts March 31, March 31, Balance as of beginning of fiscal year $ 6.0 $ 5.9 Expense to increase the reserve 0.1 0.3 Write-off of uncollectible accounts (0.4 ) (0.3 ) Balance as of period end $ 5.7 $ 5.9
Schedule of Contract Assets and Liabilities	(in millions) Contract Assets Short-term March 31, March 31, Balance as of beginning of fiscal year $ 51.2 $ 36.5 Recognized in current year 23.9 23.4 Reclassified to accounts receivable (26.4 ) (22.1 ) Impairment — — Reclassification to/from long-term — 0.8 Balance as of period end $ 48.7 $ 38.6 Long-term March 31, March 31, Balance as of beginning of fiscal year $ 0.1 $ 16.9 Recognized in current year — — Reclassified to accounts receivable — — Impairment — — Reclassification to/from short-term — (0.8 ) Balance as of period end $ 0.1 $ 16.1 (in millions) Contract Liabilities Short-term March 31, March 31, Balance as of beginning of fiscal year $ 71.4 $ 69.7 Recognized in current year 38.6 8.4 Amounts in beginning balance reclassified to revenue (29.3 ) (14.1 ) Current year amounts reclassified to revenue (2.8 ) (0.3 ) Other — — Reclassification to/from long-term — 2.5 Balance as of period end $ 77.9 $ 66.2 Long-term March 31, March 31, Balance as of beginning of fiscal year $ 7.3 $ 22.2 Recognized in current year 0.3 0.2 Amounts in beginning balance reclassified to revenue (0.3 ) (0.2 ) Current year amounts reclassified to revenue — — Other — — Reclassification to/from short-term — (2.5 ) Balance as of period end $ 7.3 $ 19.7

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories at March 31, 2019 and December 31, 2018 were as follows (in millions): March 31, December 31, Raw materials and supplies $ 212.5 $ 191.5 Work-in-process 941.3 914.1 Finished goods 192.4 191.1 Total inventories at current cost 1,346.2 1,296.7 Adjustment from current cost to LIFO cost basis 4.7 2.9 Inventory valuation reserves (96.5 ) (88.5 ) Total inventories, net $ 1,254.4 $ 1,211.1
Schedule of Inventory Valuation Impact on Income	Impacts to cost of sales for changes in the LIFO costing methodology and associated NRV inventory reserves were as follows (in millions): Three months ended March 31, 2019 2018 LIFO benefit (charge) $ 1.8 $ (8.2 ) NRV benefit (charge) (1.9 ) 8.2 Net cost of sales impact $ (0.1 ) $ —

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Property Plant And Equipment	Property, plant and equipment at March 31, 2019 and December 31, 2018 was as follows (in millions): March 31, December 31, Land $ 31.6 $ 31.5 Buildings 853.9 851.7 Equipment and leasehold improvements 3,653.0 3,622.7 4,538.5 4,505.9 Accumulated depreciation and amortization (2,067.8 ) (2,030.9 ) Total property, plant and equipment, net $ 2,470.7 $ 2,475.0

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of Debt Instruments	Debt at March 31, 2019 and December 31, 2018 was as follows (in millions): March 31, December 31, Allegheny Technologies 5.875% Notes due 2023 (a) $ 500.0 $ 500.0 Allegheny Technologies 5.95% Notes due 2021 500.0 500.0 Allegheny Technologies 4.75% Convertible Senior Notes due 2022 287.5 287.5 Allegheny Ludlum 6.95% Debentures due 2025 150.0 150.0 Term Loan due 2022 100.0 100.0 U.S. revolving credit facility — — Foreign credit facilities — — Other 14.8 15.0 Debt issuance costs (9.7 ) (10.4 ) Total debt 1,542.6 1,542.1 Short-term debt and current portion of long-term debt 6.4 6.6 Total long-term debt $ 1,536.2 $ 1,535.5 (a) Bearing interest at 7.875% effective February 15, 2016.

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Schedule of Lease Cost	The following represents the components of lease cost and other information for both operating and financing leases for the three months ending March 31, 2019 : ($ in millions) Three months ended March 31, 2019 Lease Cost Finance Lease Cost: Amortization of right of use asset $ 0.2 Interest on lease liabilities 0.1 Operating lease cost 5.1 Short-term lease cost 0.9 Variable lease cost 0.1 Sublease income — Total lease cost $ 6.4 Other information Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from finance leases $ 0.1 Operating cash flows from operating leases $ 5.1 Financing cash flows from finance leases $ 0.3 Right of use assets obtained in exchange for new finance lease liabilities $ 3.6 Right of use assets obtained in exchange for new operating lease liabilities $ 12.4 Weighted average remaining lease term - finance leases 4.22 years Weighted average remaining lease term - operating leases 5.88 years Weighted average discount rate - finance leases 6.3 % Weighted average discount rate - operating leases 7.4 %
Schedule of Operating Lease Liability Maturities	The following table reconciles future minimum undiscounted rental commitments for operating leases to the operating lease liabilities recorded on the consolidated balance sheet as of March 31, 2019 (in millions): March 31, 2019 Remainder of 2019 $ 14.4 2020 16.3 2021 14.6 2022 11.7 2023 8.2 2024 and Thereafter 18.9 Total undiscounted lease payments $ 84.1 Present value adjustment (17.1 ) Operating lease liabilities $ 67.0
Schedule of Finance Lease Liability Maturities	The following table reconciles future minimum undiscounted rental commitments for finance leases to the finance lease liabilities recorded on the consolidated balance sheet as of March 31, 2019 (in millions): March 31, 2019 Remainder of 2019 $ 1.4 2020 1.8 2021 1.6 2022 1.2 2023 1.0 2024 and Thereafter 0.1 Total undiscounted lease payments $ 7.1 Present value adjustment (0.4 ) Finance lease liabilities $ 6.7

Derivative Financial Instrume_2

Derivative Financial Instruments and Hedging (Tables)	3 Months Ended
	Mar. 31, 2019
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) Asset derivatives Balance sheet location March 31, December 31, Derivatives designated as hedging instruments: Foreign exchange contracts Prepaid expenses and other current assets $ 0.3 $ — Natural gas contacts Prepaid expenses and other current assets 0.3 0.8 Nickel and other raw material contracts Prepaid expenses and other current assets 4.6 1.2 Natural gas contracts Other assets — 0.2 Nickel and other raw material contracts Other assets 2.4 0.8 Total derivatives designated as hedging instruments 7.6 3.0 Derivatives not designated as hedging instruments: Foreign exchange contracts Prepaid expenses and other current assets 0.5 0.4 Total derivatives not designated as hedging instruments 0.5 0.4 Total asset derivatives $ 8.1 $ 3.4 Liability derivatives Balance sheet location Derivatives designated as hedging instruments: Interest rate swap Accrued liabilities $ 0.3 $ 0.2 Foreign exchange contracts Accrued liabilities — 0.6 Natural gas contracts Accrued liabilities 0.1 0.1 Nickel and other raw material contracts Accrued liabilities 1.9 6.8 Interest rate swap Other long-term liabilities 0.3 0.3 Natural gas contracts Other long-term liabilities 0.2 0.3 Nickel and other raw material contracts Other long-term liabilities 0.5 2.1 Total derivatives designated as hedging instruments 3.3 10.4 Total liability derivatives $ 3.3 $ 10.4
Schedule Of Derivative Instruments Gain Loss In Statement Of Financial Performance	Activity with regard to derivatives designated as cash flow hedges for the three month periods ended March 31, 2019 and 2018 was as follows (in millions): Amount of Gain (Loss) Recognized in OCI on Derivatives Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (a) Three months ended March 31, Three months ended March 31, Derivatives in Cash Flow Hedging Relationships 2019 2018 2019 2018 Nickel and other raw material contracts $ 8.3 $ 3.1 $ (0.4 ) $ 2.8 Natural gas contracts (0.4 ) 0.2 0.1 (0.3 ) Foreign exchange contracts 0.3 (0.8 ) (0.3 ) (0.2 ) Interest rate swap (0.2 ) — (0.1 ) — Total $ 8.0 $ 2.5 $ (0.7 ) $ 2.3 (a) The gains (losses) reclassified from accumulated OCI into income related to the derivatives, with the exception of the interest rate swap, are presented in cost of sales in the same period or periods in which the hedged item affects earnings. The gains (losses) reclassified from accumulated OCI into income on the interest rate swap are presented in interest expense in the same period as the interest expense on the Term Loan is recognized in earnings.
Schedule Of Derivative Instruments Not Designated as Hedging Instruments	These derivatives that are not designated as hedging instruments were as follows: (In millions) Amount of Gain (Loss) Recognized in Income on Derivatives Three months ended March 31, Derivatives Not Designated as Hedging Instruments 2019 2018 Foreign exchange contracts $ 0.1 $ (0.2 )

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value By Balance Sheet Grouping	The estimated fair value of financial instruments at March 31, 2019 was as follows: Fair Value Measurements at Reporting Date Using (In millions) Total Carrying Amount Total Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Cash and cash equivalents $ 217.0 $ 217.0 $ 217.0 $ — Derivative financial instruments: Assets 8.1 8.1 — 8.1 Liabilities 3.3 3.3 — 3.3 Debt (a) 1,552.3 1,866.6 1,751.8 114.8 The estimated fair value of financial instruments at December 31, 2018 was as follows: Fair Value Measurements at Reporting Date Using (In millions) Total Carrying Amount Total Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Cash and cash equivalents $ 382.0 $ 382.0 $ 382.0 $ — Derivative financial instruments: Assets 3.4 3.4 — 3.4 Liabilities 10.4 10.4 — 10.4 Debt (a) 1,552.5 1,739.4 1,624.4 115.0 (a) The total carrying amount for debt excludes debt issuance costs related to the recognized debt liability which is presented in the consolidated balance sheet as a direct reduction from the carrying amount of the debt liability.

Retirement Benefits (Tables)

Retirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2019
Retirement Benefits [Abstract]
Schedule Of Defined Benefit Plans Disclosures [Table Text Block]	For the three month periods ended March 31, 2019 and 2018 , the components of pension and other postretirement benefit expense for the Company’s defined benefit plans included the following (in millions): Pension Benefits Other Postretirement Benefits Three months ended March 31, Three months ended March 31, 2019 2018 2019 2018 Service cost - benefits earned during the year $ 3.2 $ 4.2 $ 0.5 $ 0.6 Interest cost on benefits earned in prior years 26.3 26.1 3.7 3.1 Expected return on plan assets (32.8 ) (39.5 ) — — Amortization of prior service cost (credit) 0.1 0.1 (0.7 ) (0.7 ) Amortization of net actuarial loss 18.4 16.5 3.3 2.7 Total retirement benefit expense $ 15.2 $ 7.4 $ 6.8 $ 5.7

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 2018 Total sales: High Performance Materials & Components $ 623.9 $ 579.4 Flat Rolled Products 427.2 439.1 1,051.1 1,018.5 Intersegment sales: High Performance Materials & Components 22.7 18.7 Flat Rolled Products 23.6 20.8 46.3 39.5 Sales to external customers: High Performance Materials & Components 601.2 560.7 Flat Rolled Products 403.6 418.3 $ 1,004.8 $ 979.0 Three months ended March 31, 2019 2018 Operating profit (loss): High Performance Materials & Components $ 72.6 $ 85.5 Flat Rolled Products (10.9 ) 10.9 Total operating profit 61.7 96.4 LIFO and net realizable value reserves (0.1 ) — Corporate expenses (16.6 ) (13.2 ) Closed operations and other expenses (3.1 ) (8.1 ) Gain on joint venture deconsolidation (See Note 5) — 15.9 Interest expense, net (24.8 ) (25.5 ) Income before income taxes $ 17.1 $ 65.5

Per Share Information (Tables)

Per Share Information (Tables)	3 Months Ended
	Mar. 31, 2019
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 per common share: Three months ended (In millions, except per share amounts) March 31, 2019 2018 Numerator: Numerator for basic income per common share – Net income attributable to ATI $ 15.0 $ 58.0 Effect of dilutive securities: 4.75% Convertible Senior Notes due 2022 — 3.2 Numerator for diluted income per common share – Net income attributable to ATI after assumed conversions $ 15.0 $ 61.2 Denominator: Denominator for basic net income per common share – weighted average shares 125.4 125.0 Effect of dilutive securities: Share-based compensation 0.7 0.6 4.75% Convertible Senior Notes due 2022 — 19.9 Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions 126.1 145.5 Basic net income attributable to ATI per common share $ 0.12 $ 0.46 Diluted net income attributable to ATI per common share $ 0.12 $ 0.42

Financial Information for Sub_2

Financial Information for Subsidiary and Guarantor Parent (Tables)	3 Months Ended
	Mar. 31, 2019
Condensed Statement of Income Captions [Line Items]
Balance Sheets	Balance Sheets March 31, 2019 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Assets: Cash and cash equivalents $ 0.3 $ 12.5 $ 204.2 $ — $ 217.0 Accounts receivable, net — 157.0 408.1 — 565.1 Intercompany notes receivable — — 4,158.6 (4,158.6 ) — Short-term contract assets — — 48.7 — 48.7 Inventories, net — 250.4 1,004.0 — 1,254.4 Prepaid expenses and other current assets 7.0 47.7 38.0 — 92.7 Total current assets 7.3 467.6 5,861.6 (4,158.6 ) 2,177.9 Property, plant and equipment, net 2.7 1,538.0 930.0 — 2,470.7 Goodwill — — 536.8 — 536.8 Intercompany notes receivable — — 200.0 (200.0 ) — Investment in subsidiaries 6,183.1 37.7 — (6,220.8 ) — Other assets 43.0 54.1 208.5 — 305.6 Total assets $ 6,236.1 $ 2,097.4 $ 7,736.9 $ (10,579.4 ) $ 5,491.0 Liabilities and stockholders’ equity: Accounts payable $ 5.1 $ 174.7 $ 275.5 $ — $ 455.3 Accrued liabilities 27.3 74.8 118.3 — 220.4 Intercompany notes payable 2,186.7 1,971.9 — (4,158.6 ) — Short-term contract liabilities — 50.3 27.6 — 77.9 Short-term debt and current portion of long-term debt 0.4 0.1 5.9 — 6.4 Total current liabilities 2,219.5 2,271.8 427.3 (4,158.6 ) 760.0 Long-term debt 1,280.1 149.7 106.4 — 1,536.2 Intercompany notes payable — 200.0 — (200.0 ) — Accrued postretirement benefits — 255.4 54.1 — 309.5 Pension liabilities 653.4 3.8 43.9 — 701.1 Deferred income taxes 14.5 — — — 14.5 Other long-term liabilities 22.0 36.8 64.3 — 123.1 Total liabilities 4,189.5 2,917.5 696.0 (4,358.6 ) 3,444.4 Total stockholders’ equity (deficit) 2,046.6 (820.1 ) 7,040.9 (6,220.8 ) 2,046.6 Total liabilities and stockholders’ equity $ 6,236.1 $ 2,097.4 $ 7,736.9 $ (10,579.4 ) $ 5,491.0 Balance Sheets December 31, 2018 Guarantor Non-guarantor (In millions) Parent Subsidiary Subsidiaries Eliminations Consolidated Assets: Cash and cash equivalents $ 0.1 $ 10.8 $ 371.1 $ — $ 382.0 Accounts receivable, net — 126.3 401.5 — 527.8 Intercompany notes receivable — — 3,968.8 (3,968.8 ) — Short-term contract assets — — 51.2 — 51.2 Inventories, net — 216.1 995.0 — 1,211.1 Prepaid expenses and other current assets 12.9 29.3 32.4 — 74.6 Total current assets 13.0 382.5 5,820.0 (3,968.8 ) 2,246.7 Property, plant and equipment, net 1.7 1,548.4 924.9 — 2,475.0 Goodwill — — 534.7 — 534.7 Intercompany notes receivable — — 200.0 (200.0 ) — Investment in subsidiaries 6,096.4 37.7 — (6,134.1 ) — Other assets 35.6 30.7 179.1 — 245.4 Total assets $ 6,146.7 $ 1,999.3 $ 7,658.7 $ (10,302.9 ) $ 5,501.8 Liabilities and stockholders’ equity: Accounts payable $ 3.3 $ 177.5 $ 318.0 $ — $ 498.8 Accrued liabilities 59.1 71.7 129.3 — 260.1 Intercompany notes payable 2,102.8 1,866.0 — (3,968.8 ) — Short-term contract liabilities — 33.0 38.4 — 71.4 Short-term debt and current portion of long-term debt 0.2 0.7 5.7 — 6.6 Total current liabilities 2,165.4 2,148.9 491.4 (3,968.8 ) 836.9 Long-term debt 1,278.8 151.8 104.9 — 1,535.5 Intercompany notes payable — 200.0 — (200.0 ) — Accrued postretirement benefits — 259.2 59.2 — 318.4 Pension liabilities 681.6 4.0 44.4 — 730.0 Deferred income taxes 12.9 — — — 12.9 Other long-term liabilities 16.4 17.6 42.5 — 76.5 Total liabilities 4,155.1 2,781.5 742.4 (4,168.8 ) 3,510.2 Total stockholders’ equity (deficit) 1,991.6 (782.2 ) 6,916.3 (6,134.1 ) 1,991.6 Total liabilities and stockholders’ equity $ 6,146.7 $ 1,999.3 $ 7,658.7 $ (10,302.9 ) $ 5,501.8
Statements of Operations and Comprehensive Income	Allegheny Technologies Incorporated Financial Information for Subsidiary and Guarantor Parent Statements of Income and Comprehensive Income For the three months ended March 31, 2019 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Sales $ — $ 335.5 $ 669.3 $ — $ 1,004.8 Cost of sales 3.2 318.4 552.1 — 873.7 Gross profit (loss) (3.2 ) 17.1 117.2 — 131.1 Selling and administrative expenses 30.4 7.4 30.2 — 68.0 Operating income (loss) (33.6 ) 9.7 87.0 — 63.1 Nonoperating retirement benefit expense (11.7 ) (6.2 ) (0.4 ) — (18.3 ) Interest income (expense), net (37.9 ) (33.9 ) 47.0 — (24.8 ) Other income (loss) including equity in income of unconsolidated subsidiaries 100.3 (2.9 ) (0.4 ) (99.9 ) (2.9 ) Income (loss) before income tax provision (benefit) 17.1 (33.3 ) 133.2 (99.9 ) 17.1 Income tax provision (benefit) 0.8 (8.0 ) 29.9 (21.9 ) 0.8 Net income (loss) 16.3 (25.3 ) 103.3 (78.0 ) 16.3 Less: Net income attributable to noncontrolling interests — — 1.3 — 1.3 Net income (loss) attributable to ATI $ 16.3 $ (25.3 ) $ 102.0 $ (78.0 ) $ 15.0 Comprehensive income (loss) attributable to ATI $ 59.8 $ (22.1 ) $ 107.8 $ (92.2 ) $ 53.3 Allegheny Technologies Incorporated Financial Information for Subsidiary and Guarantor Parent Statements of Operations and Comprehensive Income For the three months ended March 31, 2018 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Sales $ — $ 346.4 $ 632.6 $ — $ 979.0 Cost of sales 4.1 323.2 503.1 — 830.4 Gross profit (loss) (4.1 ) 23.2 129.5 — 148.6 Selling and administrative expenses 23.7 10.3 33.1 — 67.1 Operating income (loss) (27.8 ) 12.9 96.4 — 81.5 Nonoperating retirement benefit expense (3.1 ) (4.9 ) (0.3 ) — (8.3 ) Interest income (expense), net (33.0 ) (25.7 ) 33.2 — (25.5 ) Other income (loss) including equity in income of unconsolidated subsidiaries 129.4 16.8 0.5 (128.9 ) 17.8 Income (loss) before income tax provision (benefit) 65.5 (0.9 ) 129.8 (128.9 ) 65.5 Income tax provision (benefit) 5.0 0.2 20.2 (20.4 ) 5.0 Net income (loss) 60.5 (1.1 ) 109.6 (108.5 ) 60.5 Less: Net income attributable to noncontrolling interests — — 2.5 — 2.5 Net income (loss) attributable to ATI $ 60.5 $ (1.1 ) $ 107.1 $ (108.5 ) $ 58.0 Comprehensive income (loss) attributable to ATI $ 103.0 $ 1.3 $ 124.0 $ (134.7 ) $ 93.6
Condensed Statements of Cash Flows	Condensed Statements of Cash Flows For the three months ended March 31, 2019 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Cash flows provided by (used in) operating activities $ (53.5 ) $ (115.8 ) $ 39.3 $ — $ (130.0 ) Investing Activities: Purchases of property, plant and equipment (0.3 ) (2.4 ) (20.8 ) — (23.5 ) Net receipts/(payments) on intercompany activity — — (184.0 ) 184.0 — Asset disposals and other (0.1 ) — — — (0.1 ) Cash flows provided by (used in) investing activities (0.4 ) (2.4 ) (204.8 ) 184.0 (23.6 ) Financing Activities: Payments on long-term debt and finance leases (0.1 ) — (1.4 ) — (1.5 ) Net receipts/(payments) on intercompany activity 64.1 119.9 — (184.0 ) — Shares repurchased for income tax withholding on share-based compensation and other (9.9 ) — — — (9.9 ) Cash flows provided by (used in) financing activities 54.1 119.9 (1.4 ) (184.0 ) (11.4 ) Increase (decrease) in cash and cash equivalents $ 0.2 $ 1.7 $ (166.9 ) $ — $ (165.0 ) Condensed Statements of Cash Flows For the three months ended March 31, 2018 (In millions) Guarantor Parent Subsidiary Non-guarantor Subsidiaries Eliminations Consolidated Cash flows provided by (used in) operating activities $ (51.2 ) $ (36.1 ) $ 40.2 $ — $ (47.1 ) Investing Activities: Purchases of property, plant and equipment (0.4 ) (7.3 ) (33.9 ) — (41.6 ) Net receipts/(payments) on intercompany activity — — (88.1 ) 88.1 — Asset disposals and other — 0.1 — — 0.1 Cash flows provided by (used in) investing activities (0.4 ) (7.2 ) (122.0 ) 88.1 (41.5 ) Financing Activities: Borrowings on long-term debt — — 6.4 — 6.4 Payments on long-term debt and finance leases (0.1 ) (0.1 ) (1.1 ) — (1.3 ) Net borrowings under credit facilities — — 50.9 — 50.9 Net receipts/(payments) on intercompany activity 57.7 30.4 — (88.1 ) — Sale to noncontrolling interests — 4.7 2.7 — 7.4 Shares repurchased for income tax withholding on share-based compensation (6.5 ) — — — (6.5 ) Cash flows provided by (used in) financing activities 51.1 35.0 58.9 (88.1 ) 56.9 Decrease in cash and cash equivalents $ (0.5 ) $ (8.3 ) $ (22.9 ) $ — $ (31.7 )

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
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 March 31, 2019 were as follows (in millions): Post- retirement benefit plans Currency translation adjustment Derivatives Deferred Tax Asset Valuation Allowance Total Attributable to ATI: Balance, December 31, 2018 $ (1,005.8 ) $ (73.9 ) $ (4.8 ) $ (49.3 ) $ (1,133.8 ) OCI before reclassifications — 5.8 8.0 — 13.8 Amounts reclassified from AOCI (a) 16.1 (b) — (c) 0.7 (d) 7.7 24.5 Net current-period OCI 16.1 5.8 8.7 7.7 38.3 Balance, March 31, 2019 $ (989.7 ) $ (68.1 ) $ 3.9 $ (41.6 ) $ (1,095.5 ) Attributable to noncontrolling interests: Balance, December 31, 2018 $ — $ 11.1 $ — $ — $ 11.1 OCI before reclassifications — 5.2 — — 5.2 Amounts reclassified from AOCI — (b) — — — — Net current-period OCI — 5.2 — — 5.2 Balance, March 31, 2019 $ — $ 16.3 $ — $ — $ 16.3 (a) Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 10). (b) No amounts were reclassified to earnings. (c) Amounts related to derivatives are included in cost of goods sold or interest expense in the period or periods the hedged item affects earnings (see Note 8). (d) Represents the net change in deferred tax asset valuation allowances on changes in AOCI balances between the balance sheet dates. The changes in AOCI by component, net of tax, for the three month period ended March 31, 2018 were as follows (in millions): Post- retirement benefit plans Currency translation adjustment Derivatives Deferred Tax Asset Valuation Allowance Total Attributable to ATI: Balance, December 31, 2017 $ (954.5 ) $ (53.5 ) $ 9.0 $ (28.8 ) $ (1,027.8 ) OCI before reclassifications — 16.7 2.5 — 19.2 Amounts reclassified from AOCI (a) 14.3 (b) — (c) (2.3 ) 4.4 16.4 Net current-period OCI 14.3 16.7 0.2 4.4 35.6 Balance, March 31, 2018 $ (940.2 ) $ (36.8 ) $ 9.2 $ (24.4 ) $ (992.2 ) Attributable to noncontrolling interests: Balance, December 31, 2017 $ — $ 17.3 $ — $ — $ 17.3 OCI before reclassifications — 6.9 — — 6.9 Amounts reclassified from AOCI — (b) — — — — Net current-period OCI — 6.9 — — $ 6.9 Balance, March 31, 2018 $ — $ 24.2 $ — $ — $ 24.2 (a) Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 10). (b) No amounts were reclassified to earnings. (c) Amounts related to derivatives are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 8).
Reclassification out of Accumulated Other Comprehensive Income	Reclassifications out of AOCI for the three month periods ended March 31, 2019 and 2018 were as follows: Amount reclassified from AOCI Details about AOCI Components (In millions) Three months ended March 31, 2019 Three months ended March 31, 2018 Affected line item in the statements of income Postretirement benefit plans Prior service credit $ 0.6 $ 0.6 (a) Actuarial losses (21.7 ) (19.2 ) (a) (21.1 ) (18.6 ) (c) Total before tax (5.0 ) (4.3 ) Tax benefit (d) $ (16.1 ) $ (14.3 ) Net of tax Derivatives Nickel and other raw material contracts $ (0.5 ) $ 3.7 (b) Natural gas contracts 0.1 (0.4 ) (b) Foreign exchange contracts (0.4 ) (0.3 ) (b) Interest rate swap (0.1 ) — (b) (0.9 ) 3.0 (c) Total before tax (0.2 ) 0.7 Tax provision (benefit) (d) $ (0.7 ) $ 2.3 Net of tax (a) Amounts are reported in nonoperating retirement benefit expense (see Note 10). (b) Amounts related to derivatives, with the exception of the interest rate swap, are included in cost of goods sold in the period or periods the hedged item affects earnings. Amounts related to the interest rate swap are included in interest expense in the same period as the interest expense on the Term Loan is recognized in earnings (see Note 8). (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 income. (d) These amounts exclude the impact of any deferred tax asset valuation allowances, when applicable.

Accounting Policies (Accounting

Accounting Policies (Accounting Pronouncements) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue recognition [Line Items]
Impact of new accounting principle on prior period operating income	$ 63.1	$ 81.5
Unfavorable impact on pre-tax operating results	$ (17.1)	$ (65.5)

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Narrative (Details)	3 Months Ended
	Mar. 31, 2019USD ($)segment	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2018USD ($)
Revenue recognition [Line Items]
Inventories, net	$ 1,254,400,000		$ 1,211,100,000
Adjustment from current cost to LIFO cost basis	(4,700,000)		(2,900,000)
Sales	1,004,800,000	$ 979,000,000
Cost of sales	873,700,000	830,400,000
Short-term contract assets	48,700,000	38,600,000	51,200,000	$ 36,500,000
Long-term contract assets	100,000	16,100,000	100,000	16,900,000
Accrued liabilities	220,400,000		260,100,000
Other long-term liabilities	123,100,000		76,500,000
Short-term contract liabilities	77,900,000	66,200,000	71,400,000	69,700,000
Long-term contract liabilities	$ 7,300,000	19,700,000	7,300,000	$ 22,200,000
Number of business segments | segment	2
Revenue, Performance Obligation [Abstract]
Confirmed order backlog	$ 2,590,000,000	2,050,000,000
Confirmed orders with current performance obligations	0.80
Accounts receivable with customers	570,800,000		533,800,000
Contract costs for obtaining and fulfilling contracts	5,200,000		$ 5,200,000
Amortization of contract costs	$ 300,000	$ 300,000

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 1,004.8	$ 979
Percent of revenue	100.00%	100.00%
Total High-Value Products
Disaggregation of Revenue [Line Items]
Percent of revenue	87.00%	86.00%
Nickel-based alloys and specialty alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	30.00%	30.00%
Precision forgings, castings and components
Disaggregation of Revenue [Line Items]
Percent of revenue	19.00%	21.00%
Titanium and titanium-based alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	19.00%	16.00%
Precision and engineered strip
Disaggregation of Revenue [Line Items]
Percent of revenue	13.00%	14.00%
Zirconium and related alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	6.00%	5.00%
Total Standard Products
Disaggregation of Revenue [Line Items]
Percent of revenue	13.00%	14.00%
Stainless steel sheet
Disaggregation of Revenue [Line Items]
Percent of revenue	7.00%	8.00%
Specialty stainless sheet
Disaggregation of Revenue [Line Items]
Percent of revenue	4.00%	4.00%
Stainless steel plate and other
Disaggregation of Revenue [Line Items]
Percent of revenue	2.00%	2.00%
United States
Disaggregation of Revenue [Line Items]
Revenue	$ 621.1	$ 554.3
Europe
Disaggregation of Revenue [Line Items]
Revenue	211	225.5
Asia
Disaggregation of Revenue [Line Items]
Revenue	123.2	150.8
Canada
Disaggregation of Revenue [Line Items]
Revenue	26.4	27.2
South America, Middle East and other
Disaggregation of Revenue [Line Items]
Revenue	23.1	21.2
Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue	525.6	462.4
Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue	112.8	152.7
Automotive
Disaggregation of Revenue [Line Items]
Revenue	76.9	79.1
Construction/Mining
Disaggregation of Revenue [Line Items]
Revenue	57.9	55.6
Electrical Energy
Disaggregation of Revenue [Line Items]
Revenue	55.7	52.2
Food Equipment & Appliances
Disaggregation of Revenue [Line Items]
Revenue	53.2	58.9
Medical
Disaggregation of Revenue [Line Items]
Revenue	46.1	44.9
Electronics/Computers/Communications
Disaggregation of Revenue [Line Items]
Revenue	34.1	32.9
Other
Disaggregation of Revenue [Line Items]
Revenue	42.5	40.3
Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	1,051.1	1,018.5
Operating Segments | High Performance Materials & Components
Disaggregation of Revenue [Line Items]
Revenue	$ 623.9	$ 579.4
Percent of revenue	100.00%	100.00%
Operating Segments | High Performance Materials & Components | Total High-Value Products
Disaggregation of Revenue [Line Items]
Percent of revenue	100.00%	100.00%
Operating Segments | High Performance Materials & Components | Nickel-based alloys and specialty alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	31.00%	29.00%
Operating Segments | High Performance Materials & Components | Precision forgings, castings and components
Disaggregation of Revenue [Line Items]
Percent of revenue	32.00%	38.00%
Operating Segments | High Performance Materials & Components | Titanium and titanium-based alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	27.00%	24.00%
Operating Segments | High Performance Materials & Components | Precision and engineered strip
Disaggregation of Revenue [Line Items]
Percent of revenue	0.00%	0.00%
Operating Segments | High Performance Materials & Components | Zirconium and related alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	10.00%	9.00%
Operating Segments | High Performance Materials & Components | Total Standard Products
Disaggregation of Revenue [Line Items]
Percent of revenue	0.00%	0.00%
Operating Segments | High Performance Materials & Components | Stainless steel sheet
Disaggregation of Revenue [Line Items]
Percent of revenue	0.00%	0.00%
Operating Segments | High Performance Materials & Components | Specialty stainless sheet
Disaggregation of Revenue [Line Items]
Percent of revenue	0.00%	0.00%
Operating Segments | High Performance Materials & Components | Stainless steel plate and other
Disaggregation of Revenue [Line Items]
Percent of revenue	0.00%	0.00%
Operating Segments | High Performance Materials & Components | United States
Disaggregation of Revenue [Line Items]
Revenue	$ 336	$ 289.8
Operating Segments | High Performance Materials & Components | Europe
Disaggregation of Revenue [Line Items]
Revenue	178.3	197
Operating Segments | High Performance Materials & Components | Asia
Disaggregation of Revenue [Line Items]
Revenue	52.8	48.3
Operating Segments | High Performance Materials & Components | Canada
Disaggregation of Revenue [Line Items]
Revenue	19.1	16.6
Operating Segments | High Performance Materials & Components | South America, Middle East and other
Disaggregation of Revenue [Line Items]
Revenue	15	9
Operating Segments | High Performance Materials & Components | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue	465.1	426.7
Operating Segments | High Performance Materials & Components | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue	16.7	15.2
Operating Segments | High Performance Materials & Components | Automotive
Disaggregation of Revenue [Line Items]
Revenue	3.6	2.6
Operating Segments | High Performance Materials & Components | Construction/Mining
Disaggregation of Revenue [Line Items]
Revenue	18.5	17.6
Operating Segments | High Performance Materials & Components | Electrical Energy
Disaggregation of Revenue [Line Items]
Revenue	27.3	30.8
Operating Segments | High Performance Materials & Components | Food Equipment & Appliances
Disaggregation of Revenue [Line Items]
Revenue	0.1	0.1
Operating Segments | High Performance Materials & Components | Medical
Disaggregation of Revenue [Line Items]
Revenue	42.7	41.2
Operating Segments | High Performance Materials & Components | Electronics/Computers/Communications
Disaggregation of Revenue [Line Items]
Revenue	1.1	1.5
Operating Segments | High Performance Materials & Components | Other
Disaggregation of Revenue [Line Items]
Revenue	26.1	25
Operating Segments | Flat Rolled Products
Disaggregation of Revenue [Line Items]
Revenue	$ 427.2	$ 439.1
Percent of revenue	100.00%	100.00%
Operating Segments | Flat Rolled Products | Total High-Value Products
Disaggregation of Revenue [Line Items]
Percent of revenue	68.00%	67.00%
Operating Segments | Flat Rolled Products | Nickel-based alloys and specialty alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	29.00%	31.00%
Operating Segments | Flat Rolled Products | Precision forgings, castings and components
Disaggregation of Revenue [Line Items]
Percent of revenue	0.00%	0.00%
Operating Segments | Flat Rolled Products | Titanium and titanium-based alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	6.00%	5.00%
Operating Segments | Flat Rolled Products | Precision and engineered strip
Disaggregation of Revenue [Line Items]
Percent of revenue	33.00%	31.00%
Operating Segments | Flat Rolled Products | Zirconium and related alloys
Disaggregation of Revenue [Line Items]
Percent of revenue	0.00%	0.00%
Operating Segments | Flat Rolled Products | Total Standard Products
Disaggregation of Revenue [Line Items]
Percent of revenue	32.00%	33.00%
Operating Segments | Flat Rolled Products | Stainless steel sheet
Disaggregation of Revenue [Line Items]
Percent of revenue	17.00%	20.00%
Operating Segments | Flat Rolled Products | Specialty stainless sheet
Disaggregation of Revenue [Line Items]
Percent of revenue	11.00%	9.00%
Operating Segments | Flat Rolled Products | Stainless steel plate and other
Disaggregation of Revenue [Line Items]
Percent of revenue	4.00%	4.00%
Operating Segments | Flat Rolled Products | United States
Disaggregation of Revenue [Line Items]
Revenue	$ 285.1	$ 264.5
Operating Segments | Flat Rolled Products | Europe
Disaggregation of Revenue [Line Items]
Revenue	32.7	28.5
Operating Segments | Flat Rolled Products | Asia
Disaggregation of Revenue [Line Items]
Revenue	70.4	102.5
Operating Segments | Flat Rolled Products | Canada
Disaggregation of Revenue [Line Items]
Revenue	7.3	10.6
Operating Segments | Flat Rolled Products | South America, Middle East and other
Disaggregation of Revenue [Line Items]
Revenue	8.1	12.2
Operating Segments | Flat Rolled Products | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue	60.5	35.7
Operating Segments | Flat Rolled Products | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue	96.1	137.5
Operating Segments | Flat Rolled Products | Automotive
Disaggregation of Revenue [Line Items]
Revenue	73.3	76.5
Operating Segments | Flat Rolled Products | Construction/Mining
Disaggregation of Revenue [Line Items]
Revenue	39.4	38
Operating Segments | Flat Rolled Products | Electrical Energy
Disaggregation of Revenue [Line Items]
Revenue	28.4	21.4
Operating Segments | Flat Rolled Products | Food Equipment & Appliances
Disaggregation of Revenue [Line Items]
Revenue	53.1	58.8
Operating Segments | Flat Rolled Products | Medical
Disaggregation of Revenue [Line Items]
Revenue	3.4	3.7
Operating Segments | Flat Rolled Products | Electronics/Computers/Communications
Disaggregation of Revenue [Line Items]
Revenue	33	31.4
Operating Segments | Flat Rolled Products | Other
Disaggregation of Revenue [Line Items]
Revenue	16.4	15.3
External Customers | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	1,004.8	979
External Customers | Operating Segments | High Performance Materials & Components
Disaggregation of Revenue [Line Items]
Revenue	601.2	560.7
External Customers | Operating Segments | Flat Rolled Products
Disaggregation of Revenue [Line Items]
Revenue	$ 403.6	$ 418.3

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Accounts Receivable Reserve for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance as of beginning of fiscal year	$ 6	$ 5.9
Expense to increase the reserve	0.1	0.3
Write-off of uncollectible accounts	(0.4)	(0.3)
Balance as of period end	$ 5.7	$ 5.9

Revenue from Contracts with C_6

Revenue from Contracts with Customers - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Contract Assets, Current [Roll Forward]
Balance as of beginning of fiscal year	$ 51.2
Recognized in current year	23.9	$ 23.4
Reclassified to accounts receivable	(26.4)	(22.1)
Impairment	0	0
Reclassification to/from long-term	0	0.8
Balance as of period end	48.7	38.6
Contract Assets, Noncurrent [Roll Forward]
Balance as of beginning of fiscal year	0.1
Recognized in current year	0	0
Reclassified to accounts receivable	0	0
Impairment	0	0
Reclassification to/from short-term	0	(0.8)
Balance as of period end	0.1	16.1
Contract Liabilities, Current [Roll Forward]
Balance as of beginning of fiscal year	71.4
Recognized in current year	38.6	8.4
Amounts in beginning balance reclassified to revenue	(29.3)	(14.1)
Current year amounts reclassified to revenue	(2.8)	(0.3)
Other	0	0
Reclassification to/from long-term	0	2.5
Balance as of period end	77.9	66.2
Contract Liabilities, Noncurrent [Roll Forward]
Balance as of beginning of fiscal year	7.3
Recognized in current year	0.3	0.2
Amounts in beginning balance reclassified to revenue	(0.3)	(0.2)
Current year amounts reclassified to revenue	0	0
Other	0	0
Reclassification to/from short-term	0	(2.5)
Balance as of period end	$ 7.3	$ 19.7

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Inventory [Line Items]
Raw materials and supplies	$ 212.5		$ 191.5
Work-in-process	941.3		914.1
Finished goods	192.4		191.1
Total inventories at current cost	1,346.2		1,296.7
Adjustment from current cost to LIFO cost basis	4.7		2.9
Inventory valuation reserves	(96.5)		(88.5)
Total inventories, net	1,254.4		1,211.1
LIFO benefit (charge)	1.8	$ (8.2)
NRV benefit (charge)	(1.9)	8.2
Net cost of sales impact	(0.1)	$ 0
Net Realizable Value Reserve [Member]
Inventory [Line Items]
Inventory valuation reserves	$ (9.9)		$ (8)

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Land	$ 31.6	$ 31.5
Buildings	853.9	851.7
Equipment and leasehold improvements	3,653	3,622.7
Property Plant And Equipment, gross	4,538.5	4,505.9
Accumulated depreciation and amortization	(2,067.8)	(2,030.9)
Total property, plant and equipment, net	2,470.7	$ 2,475
Construction in progress	$ 91.3

Joint Ventures (Details)

Joint Ventures (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended	24 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Cash and cash equivalents	$ 217	$ 109.9	$ 382		$ 141.6
Sales to noncontrolling interests	0	7.4
Gain on joint venture deconsolidation	0	15.9
Investment in subsidiaries	$ 0		0
Next Gen Alloys LLC
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage	51.00%
Cash and cash equivalents	$ 9
Sales to noncontrolling interests		2.7
Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Sales to noncontrolling interests		5	$ 12
Equity method investment ownership percentage	50.00%
Uniti
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage	50.00%
Tsingshan Group | Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage by unaffiliated entity	50.00%
VSMPO | Uniti
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage by unaffiliated entity	50.00%
Flat Rolled Products | Shanghai STAL Precision Stainless Steel Co Ltd
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage	60.00%
Cash and cash equivalents	$ 39.4
Flat Rolled Products | Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(3.3)	(0.6)
Investment in subsidiaries	7.8
Flat Rolled Products | Uniti
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 0.5	$ 0.5
Flat Rolled Products | China Baowu Steel Group Corporation Limited | Shanghai STAL Precision Stainless Steel Co Ltd
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage by unaffiliated entity	40.00%
Forecast | Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Sales to noncontrolling interests				$ 17.5

Debt Schedule of Debt (Details)

Debt Schedule of Debt (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2019	Dec. 31, 2018	Feb. 15, 2016	Dec. 31, 2013
Debt Instrument [Line Items]
Debt Issuance Costs, Net		$ (9.7)	$ (10.4)
Total Debt		1,542.6	1,542.1
Short-term debt and current portion of long-term debt		6.4	6.6
Long-term debt		1,536.2	1,535.5
Allegheny Technologies, Convertible Senior Notes, 4.75%, Due 2022
Debt Instrument [Line Items]
Debt, Gross		$ 287.5	$ 287.5
Debt Instrument, Issuer		Allegheny Technologies
Debt Instrument, Maturity Date		Jul. 1, 2022	Jul. 1, 2022
Interest rate		4.75%	4.75%
Allegheny Technologies 5.875% Notes due 2023 (a)
Debt Instrument [Line Items]
Debt, Gross	[1]	$ 500	$ 500
Debt Instrument, Issuer		Allegheny Technologies
Debt Instrument, Maturity Date		Aug. 15, 2023	Aug. 15, 2023
Interest rate		7.875%	7.875%	7.875%	5.875%
Allegheny Technologies 5.95% Notes due 2021
Debt Instrument [Line Items]
Debt, Gross		$ 500	$ 500
Debt Instrument, Issuer		Allegheny Technologies
Debt Instrument, Maturity Date		Jan. 15, 2021	Jan. 15, 2021
Interest rate		5.95%	5.95%
Allegheny Ludlum 6.95% debentures due 2025
Debt Instrument [Line Items]
Debt, Gross		$ 150	$ 150
Debt Instrument, Issuer		Allegheny Ludlum
Debt Instrument, Maturity Date		Dec. 15, 2025	Dec. 15, 2025
Interest rate		6.95%	6.95%
2022 Term Loan
Debt Instrument [Line Items]
Debt, Gross		$ 100	$ 100
Debt Instrument, Issuer		Allegheny Technologies
Debt Instrument, Maturity Date		Feb. 28, 2022	Feb. 28, 2022
Interest rate		5.44%
Domestic Bank Group $400 million asset-based credit facility
Debt Instrument [Line Items]
Short-term Debt		$ 0	$ 0
Foreign credit facilities
Debt Instrument [Line Items]
Short-term Debt		0	0
Other
Debt Instrument [Line Items]
Debt, Gross		$ 14.8	$ 15
[1]	Bearing interest at 7.875% effective February 15, 2016.

Debt Narrative (Details)

Debt Narrative (Details)		3 Months Ended
		Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Feb. 15, 2016	Dec. 31, 2013
Allegheny Technologies 5.875% Notes due 2023 (a)
Debt Instrument [Line Items]
Interest rate		7.875%		7.875%	7.875%	5.875%
Outstanding borrowings	[1]	$ 500,000,000		$ 500,000,000
Asset-based lending credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity		500,000,000
Domestic Bank Group $400 million asset-based credit facility
Debt Instrument [Line Items]
Short-term Debt		0		0
Amount utilized to support the issuance of letters of credit		35,300,000
Average borrowings during period		0	$ 53,000,000
Interest rate during period			3.50%
Domestic Bank Group $400 million asset-based credit facility | Revolving credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 400,000,000
Minimum fixed charge coverage ratio allowed in event of default		1
Percentage of borrowing capacity unavailable due to fixed charge coverage ratio covenant		10.00%
Borrowing capacity unavailable due to fixed charge coverage ratio covenant		$ 40,000,000
Minimum required liquidity number of days prior to maturity of Senior Notes		91 days
Domestic Bank Group $400 million asset-based credit facility | Revolving credit facility | Minimum | LIBOR based borrowings
Debt Instrument [Line Items]
Variable interest rate (percentage)		1.75%
Domestic Bank Group $400 million asset-based credit facility | Revolving credit facility | Minimum | Base rate borrowings
Debt Instrument [Line Items]
Variable interest rate (percentage)		1.00%
Domestic Bank Group $400 million asset-based credit facility | Revolving credit facility | Maximum | LIBOR based borrowings
Debt Instrument [Line Items]
Variable interest rate (percentage)		2.25%
Domestic Bank Group $400 million asset-based credit facility | Revolving credit facility | Maximum | Base rate borrowings
Debt Instrument [Line Items]
Variable interest rate (percentage)		1.50%
Domestic Bank Group $400 million asset-based credit facility | Letter of credit sub-facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 200,000,000
2022 Term Loan
Debt Instrument [Line Items]
Interest rate		5.44%
Minimum prepayment increments allowed		$ 50,000,000
Outstanding borrowings		100,000,000		$ 100,000,000
2022 Term Loan | Interest Rate Swap
Debt Instrument [Line Items]
Notional amount of derivative		$ 50,000,000
2022 Term Loan | LIBOR based borrowings
Debt Instrument [Line Items]
Variable interest rate (percentage)		2.50%
Allegheny Technologies, Convertible Senior Notes, 4.75%, Due 2022
Debt Instrument [Line Items]
Interest rate		4.75%		4.75%
Outstanding borrowings		$ 287,500,000		$ 287,500,000
Allegheny Technologies 5.95% Notes due 2021
Debt Instrument [Line Items]
Interest rate		5.95%		5.95%
Outstanding borrowings		$ 500,000,000		$ 500,000,000
Allegheny Technologies 5.95% Notes due 2021 | Revolving credit facility
Debt Instrument [Line Items]
Minimum required liquidity prior to maturity of Senior Notes		$ 700,000,000
[1]	Bearing interest at 7.875% effective February 15, 2016.

Leases Narrative (Details)

Leases Narrative (Details) - USD ($) $ in Millions	Apr. 01, 2019	Mar. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease, right-of-use asset			$ 51.7
Operating lease liabilities		$ 67	55.6
Operating lease, current liability			12.5
Operating lease, noncurrent liability			$ 43.1
Progress payments made on behalf of company, paid		$ 1.7
Progress payments made on behalf of company, scheduled to be paid	$ 5.8
Forecast
Lessee, Lease, Description [Line Items]
Finance lease not yet commenced, right-of-use asset to be recognized	7.5
Finance lease not yet commenced, liability to be recognized	$ 7.5

Leases Schedule of Lease Cost (

Leases Schedule of Lease Cost (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Finance Lease Cost:
Amortization of right of use asset	$ 0.2
Interest on lease liabilities	0.1
Operating lease cost	5.1
Short-term lease cost	0.9
Variable lease cost	0.1
Sublease income	0
Total lease cost	6.4
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	0.1
Operating cash flows from operating leases	5.1
Finance cash flows from finance leases	0.3
Right of use assets obtained in exchange for new finance lease liabilities	3.6
Right of use assets obtained in exchange for new operating lease liabilities	$ 12.4
Weighted average remaining lease term - finance leases	4 years 2 months 19 days
Weighted average remaining lease term - operating leases	5 years 10 months 17 days
Weighted average discount rate - finance leases	6.30%
Weighted average discount rate - operating leases	7.40%

Leases Schedule of Operating Le

Leases Schedule of Operating Lease Liability Maturities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019
Leases [Abstract]
Remainder of 2019	$ 14.4
2020	16.3
2021	14.6
2022	11.7
2023	8.2
2024 and Thereafter	18.9
Total undiscounted lease payments	84.1
Present value adjustment	(17.1)
Operating lease liabilities	$ 67	$ 55.6

Leases Schedule of Finance Leas

Leases Schedule of Finance Lease Liability Maturities (Details) $ in Millions	Mar. 31, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 1.4
2020	1.8
2021	1.6
2022	1.2
2023	1
2024 and Thereafter	0.1
Total undiscounted lease payments	7.1
Present value adjustment	(0.4)
Finance lease liabilities	$ 6.7

Derivative Financial Instrume_3

Derivative Financial Instruments and Hedging (Details) € in Millions, lb in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)lb	Mar. 31, 2018USD ($)	Mar. 31, 2019EUR (€)
Derivative Instruments Gain Loss [Line Items]
Percentage of estimated annual nickel requirements	14.00%
Percentage Of Forecasted Natural Gas Usage Hedged for 2019	55.00%
Percentage Of Forecasted Natural Gas Usage Hedged for 2020	40.00%
Net derivatives gain on hedge transactions	$ 10.5	$ 3.3
Reclassification of Cash Flow Hedge Gain (Loss) [Abstract]
Cash Flow Hedge Gain (Loss) To Be Reclassified Within Twelve Months	2.9
Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Net derivatives gain on hedge transactions	8	2.5
Cost of Sales and Interest Expense [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	$ (0.7)
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		2.3
Nickel
Derivative Instruments Gain Loss [Line Items]
Notional amount of nickel hedge (in pounds of nickel) | lb	14
Interest Rate Swap | Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Net derivatives gain on hedge transactions	$ (0.2)	0
Interest Rate Swap | Interest Expense [Member] | 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
Nickel and other raw material contracts | Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Net derivatives gain on hedge transactions	8.3	3.1
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	(0.4)	2.8
Natural gas contracts | Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Net derivatives gain on hedge transactions	(0.4)	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	0.1	(0.3)
Foreign exchange contracts | Other Comprehensive Income (Loss) [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Net derivatives gain on hedge transactions	0.3	(0.8)
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	(0.3)	(0.2)
Designated as Hedging Instrument | Foreign exchange forward | Maturity Dates Through 2019 [Member] | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Notional amount of derivative | €			€ 33
Not Designated as Hedging Instrument | Foreign exchange forward | Maturity Dates Through 2019 [Member]
Derivative Instruments Gain Loss [Line Items]
Notional amount of derivative | €			€ 7
Not Designated as Hedging Instrument | Foreign exchange contracts | Cost Of Sales
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Income Net	$ 0.1	$ (0.2)
2022 Term Loan
Derivative Instruments Gain Loss [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.44%		5.44%
2022 Term Loan | Interest Rate Swap
Derivative Instruments Gain Loss [Line Items]
Notional amount of derivative	$ 50

Derivative Financial Instrume_4

Derivative Financial Instruments and Hedging (Details2) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	$ 8.1	$ 3.4
Derivative Fair Value Of Derivative Liability	3.3	10.4
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	7.6	3
Derivative Fair Value Of Derivative Liability	3.3	10.4
Designated as Hedging Instrument | Nickel and other raw material contracts | Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	4.6	1.2
Designated as Hedging Instrument | Nickel and other raw material contracts | Other assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	2.4	0.8
Designated as Hedging Instrument | Nickel and other raw material contracts | Accrued liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	1.9	6.8
Designated as Hedging Instrument | Nickel and other raw material contracts | Other long-term liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.5	2.1
Designated as Hedging Instrument | Interest Rate Swap | Accrued liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.3	0.2
Designated as Hedging Instrument | Interest Rate Swap | Other long-term liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.3	0.3
Designated as Hedging Instrument | Natural gas contracts | Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.3	0.8
Designated as Hedging Instrument | Natural gas contracts | Other assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0	0.2
Designated as Hedging Instrument | Natural gas contracts | Accrued liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.1	0.1
Designated as Hedging Instrument | Natural gas contracts | Other long-term liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.2	0.3
Designated as Hedging Instrument | Foreign exchange contracts | Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.3	0
Designated as Hedging Instrument | Foreign exchange contracts | Accrued liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0	0.6
Not Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.5	0.4
Not Designated as Hedging Instrument | Foreign exchange contracts | Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	$ 0.5	$ 0.4

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Carrying Value Reported Amount Fair Value Disclosure
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 217	$ 382
Derivative financial instruments, Assets	8.1	3.4
Derivative Financial Instruments, liabilities	3.3	10.4
Debt	1,552.3	1,552.5
Estimate Of Fair Value Fair Value Disclosure
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	217	382
Derivative financial instruments, Assets	8.1	3.4
Derivative Financial Instruments, liabilities	3.3	10.4
Debt	1,866.6	1,739.4
Estimate Of Fair Value Fair Value Disclosure | Fair Value Inputs Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	217	382
Derivative financial instruments, Assets	0	0
Derivative Financial Instruments, liabilities	0	0
Debt	1,751.8	1,624.4
Estimate Of Fair Value Fair Value Disclosure | 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	8.1	3.4
Derivative Financial Instruments, liabilities	3.3	10.4
Debt	$ 114.8	$ 115

Retirement Benefits (Details1)

Retirement Benefits (Details1) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	$ 3.2	$ 4.2
Interest cost on benefits earned in prior years	26.3	26.1
Expected return on plan assets	(32.8)	(39.5)
Amortization of prior service cost (credit)	0.1	0.1
Amortization of net actuarial loss	18.4	16.5
Total retirement benefit expense	15.2	7.4
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	0.5	0.6
Interest cost on benefits earned in prior years	3.7	3.1
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	(0.7)	(0.7)
Amortization of net actuarial loss	3.3	2.7
Total retirement benefit expense	$ 6.8	$ 5.7

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Investments, Owned, Federal Income Tax Note [Line Items]
Income tax (provision) benefit	$ (0.8)	$ (5)
Effective income tax rate	4.70%	7.60%

Business Segments (Details)

Business Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Sales	$ 1,004.8	$ 979
Operating profit (loss)	61.7	96.4
LIFO and net realizable value reserves	(0.1)	0
Corporate expenses	(16.6)	(13.2)
Closed operations and other expenses	(3.1)	(8.1)
Gain on joint venture deconsolidation (See Note 5)	0	15.9
Interest expense, net	(24.8)	(25.5)
Income from Continuing Operations before Income Taxes, Noncontrolling Interest	17.1	65.5
Operating Segments
Segment Reporting Information [Line Items]
Sales	1,051.1	1,018.5
Operating Segments | High Performance Materials & Components
Segment Reporting Information [Line Items]
Sales	623.9	579.4
Operating profit (loss)	72.6	85.5
Operating Segments | Flat Rolled Products
Segment Reporting Information [Line Items]
Sales	427.2	439.1
Operating profit (loss)	(10.9)	10.9
Internal Customers | Operating Segments
Segment Reporting Information [Line Items]
Sales	46.3	39.5
Internal Customers | Operating Segments | High Performance Materials & Components
Segment Reporting Information [Line Items]
Sales	22.7	18.7
Internal Customers | Operating Segments | Flat Rolled Products
Segment Reporting Information [Line Items]
Sales	23.6	20.8
External Customers | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,004.8	979
External Customers | Operating Segments | High Performance Materials & Components
Segment Reporting Information [Line Items]
Sales	601.2	560.7
External Customers | Operating Segments | Flat Rolled Products
Segment Reporting Information [Line Items]
Sales	$ 403.6	$ 418.3

Business Segments - Additional

Business Segments - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
Restructuring Cost and Reserve [Line Items]
Number of business segments | segment	2
Goodwill | $	$ 536.8	$ 534.7

Per Share Information (Details)

Per Share Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Earnings Per Share Reconciliation [Abstract]
Net income attributable to ATI	$ 15	$ 58
4.75% Convertible Senor Notes due 2022	0	3.2
Net income attributable to ATI after assumed conversions	$ 15	$ 61.2
Denominator for basic net income per common share – weighted average shares	125.4	125
Share-based compensation	0.7	0.6
Effective of dilutive securities: 4.75% Convertible Senior Notes due 2022	0	19.9
Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions	126.1	145.5
Basic net income attributable to ATI per common share (in dollars per share)	$ 0.12	$ 0.46
Diluted net income attributable to ATI per common share (in dollars per share)	$ 0.12	$ 0.42
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share Amount	19.9	0
Allegheny Technologies, Convertible Senior Notes, 4.75%, Due 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Interest rate	4.75%		4.75%

Financial Information for Sub_3

Financial Information for Subsidiary and Guarantor Parent (Narrative) (Details) - Allegheny Ludlum 6.95% debentures due 2025 - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt, Gross	$ 150	$ 150
Interest rate	6.95%	6.95%

Financial Information for Sub_4

Financial Information for Subsidiary and Guarantor Parent (B.S.) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 217	$ 382	$ 109.9		$ 141.6
Accounts receivable, net	565.1	527.8
Intercompany notes receivable	0	0
Short-term contract assets	48.7	51.2	38.6	$ 36.5
Inventories, net	1,254.4	1,211.1
Prepaid expenses and other current assets	92.7	74.6
Total current assets	2,177.9	2,246.7
Property, plant and equipment, net	2,470.7	2,475
Goodwill	536.8	534.7
Intercompany notes receivable	0	0
Long-term contract assets	0.1	0.1	16.1	16.9
Investment in subsidiaries	0	0
Other assets	305.6	245.4
Total assets	5,491	5,501.8
LIABILITIES AND EQUITY
Accounts payable	455.3	498.8
Accrued liabilities	220.4	260.1
Intercompany notes payable	0	0
Short-term contract liabilities	77.9	71.4	66.2	69.7
Short-term debt and current portion of long-term debt	6.4	6.6
Total current liabilities	760	836.9
Long-term debt	1,536.2	1,535.5
Intercompany notes payable	0	0
Accrued postretirement benefits	309.5	318.4
Pension liabilities	701.1	730
Deferred income taxes	14.5	12.9
Long-term contract liabilities	7.3	7.3	19.7	$ 22.2
Other long-term liabilities	123.1	76.5
Total liabilities	3,444.4	3,510.2
Total stockholders’ equity	2,046.6	1,991.6	$ 1,963.3		$ 1,844.5
Total Liabilities and Equity	5,491	5,501.8
Reportable Legal Entities | Parent Company
ASSETS
Cash and cash equivalents	0.3	0.1
Accounts receivable, net	0	0
Intercompany notes receivable	0	0
Short-term contract assets	0	0
Inventories, net	0	0
Prepaid expenses and other current assets	7	12.9
Total current assets	7.3	13
Property, plant and equipment, net	2.7	1.7
Goodwill	0	0
Intercompany notes receivable	0	0
Investment in subsidiaries	6,183.1	6,096.4
Other assets	43	35.6
Total assets	6,236.1	6,146.7
LIABILITIES AND EQUITY
Accounts payable	5.1	3.3
Accrued liabilities	27.3	59.1
Intercompany notes payable	2,186.7	2,102.8
Short-term contract liabilities	0	0
Short-term debt and current portion of long-term debt	0.4	0.2
Total current liabilities	2,219.5	2,165.4
Long-term debt	1,280.1	1,278.8
Intercompany notes payable	0	0
Accrued postretirement benefits	0	0
Pension liabilities	653.4	681.6
Deferred income taxes	14.5	12.9
Other long-term liabilities	22	16.4
Total liabilities	4,189.5	4,155.1
Total stockholders’ equity	2,046.6	1,991.6
Total Liabilities and Equity	6,236.1	6,146.7
Reportable Legal Entities | Subsidiary
ASSETS
Cash and cash equivalents	12.5	10.8
Accounts receivable, net	157	126.3
Intercompany notes receivable	0	0
Short-term contract assets	0	0
Inventories, net	250.4	216.1
Prepaid expenses and other current assets	47.7	29.3
Total current assets	467.6	382.5
Property, plant and equipment, net	1,538	1,548.4
Goodwill	0	0
Intercompany notes receivable	0	0
Investment in subsidiaries	37.7	37.7
Other assets	54.1	30.7
Total assets	2,097.4	1,999.3
LIABILITIES AND EQUITY
Accounts payable	174.7	177.5
Accrued liabilities	74.8	71.7
Intercompany notes payable	1,971.9	1,866
Short-term contract liabilities	50.3	33
Short-term debt and current portion of long-term debt	0.1	0.7
Total current liabilities	2,271.8	2,148.9
Long-term debt	149.7	151.8
Intercompany notes payable	200	200
Accrued postretirement benefits	255.4	259.2
Pension liabilities	3.8	4
Deferred income taxes	0	0
Other long-term liabilities	36.8	17.6
Total liabilities	2,917.5	2,781.5
Total stockholders’ equity	(820.1)	(782.2)
Total Liabilities and Equity	2,097.4	1,999.3
Reportable Legal Entities | NonGuarantor Subsidiaries
ASSETS
Cash and cash equivalents	204.2	371.1
Accounts receivable, net	408.1	401.5
Intercompany notes receivable	4,158.6	3,968.8
Short-term contract assets	48.7	51.2
Inventories, net	1,004	995
Prepaid expenses and other current assets	38	32.4
Total current assets	5,861.6	5,820
Property, plant and equipment, net	930	924.9
Goodwill	536.8	534.7
Intercompany notes receivable	200	200
Investment in subsidiaries	0	0
Other assets	208.5	179.1
Total assets	7,736.9	7,658.7
LIABILITIES AND EQUITY
Accounts payable	275.5	318
Accrued liabilities	118.3	129.3
Intercompany notes payable	0	0
Short-term contract liabilities	27.6	38.4
Short-term debt and current portion of long-term debt	5.9	5.7
Total current liabilities	427.3	491.4
Long-term debt	106.4	104.9
Intercompany notes payable	0	0
Accrued postretirement benefits	54.1	59.2
Pension liabilities	43.9	44.4
Deferred income taxes	0	0
Other long-term liabilities	64.3	42.5
Total liabilities	696	742.4
Total stockholders’ equity	7,040.9	6,916.3
Total Liabilities and Equity	7,736.9	7,658.7
Eliminations
ASSETS
Cash and cash equivalents	0	0
Accounts receivable, net	0	0
Intercompany notes receivable	(4,158.6)	(3,968.8)
Short-term contract assets	0	0
Inventories, net	0	0
Prepaid expenses and other current assets	0	0
Total current assets	(4,158.6)	(3,968.8)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intercompany notes receivable	(200)	(200)
Investment in subsidiaries	(6,220.8)	(6,134.1)
Other assets	0	0
Total assets	(10,579.4)	(10,302.9)
LIABILITIES AND EQUITY
Accounts payable	0	0
Accrued liabilities	0	0
Intercompany notes payable	(4,158.6)	(3,968.8)
Short-term contract liabilities	0	0
Short-term debt and current portion of long-term debt	0	0
Total current liabilities	(4,158.6)	(3,968.8)
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	(4,358.6)	(4,168.8)
Total stockholders’ equity	(6,220.8)	(6,134.1)
Total Liabilities and Equity	$ (10,579.4)	$ (10,302.9)

Financial Information for Sub_5

Financial Information for Subsidiary and Guarantor Parent (I.S.) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Sales	$ 1,004.8	$ 979
Cost of sales	873.7	830.4
Gross profit (loss)	131.1	148.6
Selling and administrative expenses	68	67.1
Operating income (loss)	63.1	81.5
Nonoperating retirement benefit expense	(18.3)	(8.3)
Interest income (expense), net	(24.8)	(25.5)
Other income (loss) including equity in income of unconsolidated subsidiaries	(2.9)	17.8
Income (loss) before income tax provision (benefit)	17.1	65.5
Income tax provision (benefit)	0.8	5
Net income (loss)	16.3	60.5
Less: Net income attributable to noncontrolling interests	1.3	2.5
Net income (loss) attributable to ATI	15	58
Comprehensive income (loss) attributable to ATI	53.3	93.6
Reportable Legal Entities | Parent Company
Income Statement [Abstract]
Sales	0	0
Cost of sales	3.2	4.1
Gross profit (loss)	(3.2)	(4.1)
Selling and administrative expenses	30.4	23.7
Operating income (loss)	(33.6)	(27.8)
Nonoperating retirement benefit expense	(11.7)	(3.1)
Interest income (expense), net	(37.9)	(33)
Other income (loss) including equity in income of unconsolidated subsidiaries	100.3	129.4
Income (loss) before income tax provision (benefit)	17.1	65.5
Income tax provision (benefit)	0.8	5
Net income (loss)	16.3	60.5
Less: Net income attributable to noncontrolling interests	0	0
Net income (loss) attributable to ATI	16.3	60.5
Comprehensive income (loss) attributable to ATI	59.8	103
Reportable Legal Entities | Subsidiary
Income Statement [Abstract]
Sales	335.5	346.4
Cost of sales	318.4	323.2
Gross profit (loss)	17.1	23.2
Selling and administrative expenses	7.4	10.3
Operating income (loss)	9.7	12.9
Nonoperating retirement benefit expense	(6.2)	(4.9)
Interest income (expense), net	(33.9)	(25.7)
Other income (loss) including equity in income of unconsolidated subsidiaries	(2.9)	16.8
Income (loss) before income tax provision (benefit)	(33.3)	(0.9)
Income tax provision (benefit)	(8)	0.2
Net income (loss)	(25.3)	(1.1)
Less: Net income attributable to noncontrolling interests	0	0
Net income (loss) attributable to ATI	(25.3)	(1.1)
Comprehensive income (loss) attributable to ATI	(22.1)	1.3
Reportable Legal Entities | NonGuarantor Subsidiaries
Income Statement [Abstract]
Sales	669.3	632.6
Cost of sales	552.1	503.1
Gross profit (loss)	117.2	129.5
Selling and administrative expenses	30.2	33.1
Operating income (loss)	87	96.4
Nonoperating retirement benefit expense	(0.4)	(0.3)
Interest income (expense), net	47	33.2
Other income (loss) including equity in income of unconsolidated subsidiaries	(0.4)	0.5
Income (loss) before income tax provision (benefit)	133.2	129.8
Income tax provision (benefit)	29.9	20.2
Net income (loss)	103.3	109.6
Less: Net income attributable to noncontrolling interests	1.3	2.5
Net income (loss) attributable to ATI	102	107.1
Comprehensive income (loss) attributable to ATI	107.8	124
Eliminations
Income Statement [Abstract]
Sales	0	0
Cost of sales	0	0
Gross profit (loss)	0	0
Selling and administrative expenses	0	0
Operating income (loss)	0	0
Nonoperating retirement benefit expense	0	0
Interest income (expense), net	0	0
Other income (loss) including equity in income of unconsolidated subsidiaries	(99.9)	(128.9)
Income (loss) before income tax provision (benefit)	(99.9)	(128.9)
Income tax provision (benefit)	(21.9)	(20.4)
Net income (loss)	(78)	(108.5)
Less: Net income attributable to noncontrolling interests	0	0
Net income (loss) attributable to ATI	(78)	(108.5)
Comprehensive income (loss) attributable to ATI	$ (92.2)	$ (134.7)

Financial Information for Sub_6

Financial Information for Subsidiary and Guarantor Parent (Cash Flow) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Cash Flows
Cash flows provided by (used in) operating activities	$ (130)	$ (47.1)
Investing Activities:
Purchases of property, plant and equipment	(23.5)	(41.6)
Net receipts/(payments) on intercompany activity	0	0
Asset disposals and other	(0.1)	0.1
Cash used in investing activities	(23.6)	(41.5)
Financing Activities:
Borrowings on long-term debt	0	6.4
Payments on long-term debt and finance leases	(1.5)	(1.3)
Net borrowings under credit facilities	0	50.9
Net receipts/(payments) on intercompany activity	0	0
Sales to noncontrolling interests	0	7.4
Shares repurchased for income tax withholding on share-based compensation and other	(9.9)	(6.5)
Cash (used in) provided by financing activities	(11.4)	56.9
Decrease in cash and cash equivalents	(165)	(31.7)
Reportable Legal Entities | Parent Company
Statement of Cash Flows
Cash flows provided by (used in) operating activities	(53.5)	(51.2)
Investing Activities:
Purchases of property, plant and equipment	(0.3)	(0.4)
Net receipts/(payments) on intercompany activity	0	0
Asset disposals and other	(0.1)	0
Cash used in investing activities	(0.4)	(0.4)
Financing Activities:
Borrowings on long-term debt		0
Payments on long-term debt and finance leases	(0.1)	(0.1)
Net borrowings under credit facilities		0
Net receipts/(payments) on intercompany activity	64.1	57.7
Sales to noncontrolling interests		0
Shares repurchased for income tax withholding on share-based compensation and other	(9.9)	(6.5)
Cash (used in) provided by financing activities	54.1	51.1
Decrease in cash and cash equivalents	0.2	(0.5)
Reportable Legal Entities | Subsidiary
Statement of Cash Flows
Cash flows provided by (used in) operating activities	(115.8)	(36.1)
Investing Activities:
Purchases of property, plant and equipment	(2.4)	(7.3)
Net receipts/(payments) on intercompany activity	0	0
Asset disposals and other	0	0.1
Cash used in investing activities	(2.4)	(7.2)
Financing Activities:
Borrowings on long-term debt		0
Payments on long-term debt and finance leases	0	(0.1)
Net borrowings under credit facilities		0
Net receipts/(payments) on intercompany activity	119.9	30.4
Sales to noncontrolling interests		4.7
Shares repurchased for income tax withholding on share-based compensation and other	0	0
Cash (used in) provided by financing activities	119.9	35
Decrease in cash and cash equivalents	1.7	(8.3)
Reportable Legal Entities | NonGuarantor Subsidiaries
Statement of Cash Flows
Cash flows provided by (used in) operating activities	39.3	40.2
Investing Activities:
Purchases of property, plant and equipment	(20.8)	(33.9)
Net receipts/(payments) on intercompany activity	(184)	(88.1)
Asset disposals and other	0	0
Cash used in investing activities	(204.8)	(122)
Financing Activities:
Borrowings on long-term debt		6.4
Payments on long-term debt and finance leases	(1.4)	(1.1)
Net borrowings under credit facilities		50.9
Net receipts/(payments) on intercompany activity	0	0
Sales to noncontrolling interests		2.7
Shares repurchased for income tax withholding on share-based compensation and other	0	0
Cash (used in) provided by financing activities	(1.4)	58.9
Decrease in cash and cash equivalents	(166.9)	(22.9)
Eliminations
Statement of Cash Flows
Cash flows provided by (used in) operating activities	0	0
Investing Activities:
Purchases of property, plant and equipment	0	0
Net receipts/(payments) on intercompany activity	184	88.1
Asset disposals and other	0	0
Cash used in investing activities	184	88.1
Financing Activities:
Borrowings on long-term debt		0
Payments on long-term debt and finance leases	0	0
Net borrowings under credit facilities		0
Net receipts/(payments) on intercompany activity	(184)	(88.1)
Sales to noncontrolling interests		0
Shares repurchased for income tax withholding on share-based compensation and other	0	0
Cash (used in) provided by financing activities	(184)	(88.1)
Decrease in cash and cash equivalents	$ 0	$ 0

Financial Information for Sub_7

Financial Information for Subsidiary and Guarantor Parent (Changes) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Current assets	$ 2,177.9		$ 2,246.7
Assets	5,491		5,501.8
Current liabilities	760		836.9
Liabilities	3,444.4		3,510.2
Stockholders' equity	2,046.6	$ 1,963.3	$ 1,991.6	$ 1,844.5
Cash flows provided by (used in) operating activities	(130)	(47.1)
Net Cash Provided by (Used in) Investing Activities	(23.6)	(41.5)
Cash (used in) provided by financing activities	$ (11.4)	$ 56.9

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019		Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ (1,133.8)		$ (1,027.8)
OCI before reclassifications	13.8		19.2
Amounts reclassified from AOCI	24.5		16.4
Net current-period OCI	38.3		35.6
Ending balance	(1,095.5)		(992.2)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	11.1		17.3
OCI before reclassifications	5.2		6.9
Amounts reclassified from AOCI	0		0
Net current-period OCI	5.2		6.9
Ending balance	16.3		24.2
Post- retirement benefit plans [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,005.8)		(954.5)
OCI before reclassifications	0		0
Amounts reclassified from AOCI	16.1	[1]	14.3	[2]
Net current-period OCI	16.1		14.3
Ending balance	(989.7)		(940.2)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	0		0
OCI before reclassifications	0		0
Amounts reclassified from AOCI	0		0
Net current-period OCI	0		0
Ending balance	0		0
Currency translation adjustment [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(73.9)		(53.5)
OCI before reclassifications	5.8		16.7
Amounts reclassified from AOCI	0	[3]	0	[4]
Net current-period OCI	5.8		16.7
Ending balance	(68.1)		(36.8)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	11.1		17.3
OCI before reclassifications	5.2		6.9
Amounts reclassified from AOCI	0	[3]	0	[4]
Net current-period OCI	5.2		6.9
Ending balance	16.3		24.2
Derivatives [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(4.8)		9
OCI before reclassifications	8		2.5
Amounts reclassified from AOCI	0.7	[5]	(2.3)	[6]
Net current-period OCI	8.7		0.2
Ending balance	3.9		9.2
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	0		0
OCI before reclassifications	0		0
Amounts reclassified from AOCI	0		0
Net current-period OCI	0		0
Ending balance	0		0
Accumulated Deferred Tax Asset Valuation Allowance [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(49.3)		(28.8)
OCI before reclassifications	0		0
Amounts reclassified from AOCI	7.7	[7]	4.4
Net current-period OCI	7.7		4.4
Ending balance	(41.6)		(24.4)
Increase (Decrease) in Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	0		0
OCI before reclassifications	0		0
Amounts reclassified from AOCI	0		0
Net current-period OCI	0		0
Ending balance	$ 0		$ 0
[1]	Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 10).
[2]	Amounts were included in net periodic benefit cost for pension and other postretirement benefit plans (see Note 10).
[3]	No amounts were reclassified to earnings.
[4]	No amounts were reclassified to earnings.
[5]	Amounts related to derivatives are included in cost of goods sold or interest expense in the period or periods the hedged item affects earnings (see Note 8).
[6]	Amounts related to derivatives are included in cost of goods sold in the period or periods the hedged item affects earnings (see Note 8).
[7]	Represents the net change in deferred tax asset valuation allowances on changes in AOCI balances between the balance sheet dates.

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) (Details 2) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization to net income of net prior service credits		$ (0.6)	$ (0.6)
Amount reclassified from AOCI, Postretirement benefit plans, Actuarial losses		21.7	19.2
Income (loss) before income tax provision (benefit)		17.1	65.5
Income tax provision		0.8	5
Cost of sales		(873.7)	(830.4)
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	[1]	0.6	0.6
Amount reclassified from AOCI, Postretirement benefit plans, Actuarial losses	[1]	(21.7)	(19.2)
Income (loss) before income tax provision (benefit)	[2]	(21.1)	(18.6)
Income tax provision	[3]	(5)	(4.3)
Net income (loss)		(16.1)	(14.3)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income tax provision (benefit)	[2]	(0.9)	3
Income tax provision	[3]	(0.2)	0.7
Net income (loss)		(0.7)	2.3
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]
Cost of sales	[4]	(0.5)	3.7
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member] | Natural gas contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	[4]	0.1	(0.4)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member] | Foreign exchange contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	[4]	(0.4)	(0.3)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivatives [Member] | Interest Rate Swap
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense	[4]	$ (0.1)	$ 0
[1]	Amounts are reported in nonoperating retirement benefit expense (see Note 10).
[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 income.
[3]	These amounts exclude the impact of any deferred tax asset valuation allowances, when applicable.
[4]	Amounts related to derivatives, with the exception of the interest rate swap, are included in cost of goods sold in the period or periods the hedged item affects earnings. Amounts related to the interest rate swap are included in interest expense in the same period as the interest expense on the Term Loan is recognized in earnings (see Note 8).

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2019USD ($)
Components of Environmental Loss Accrual [Abstract]
Accrual For Environmental Loss Contingencies	$ 20
Accrued Environmental Loss Contingencies Current	8
Federal Superfund and comparable state-managed sites	3
Formerly owned or operated sites	16
Owned or controlled sites at which Company operations have been discontinued	1
Maximum
Loss Contingency, Estimate [Abstract]
Loss contingency maximum possible loss	$ 15