XML 49 R55.htm IDEA: XBRL DOCUMENT
v3.20.1

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue | $ 1,018.6 | $ 1,018.7 | $ 1,080.4 | $ 1,004.8 | $ 1,037.9 | $ 1,020.2 | $ 1,009.5 | $ 979.0 | $ 4,122.5 | $ 4,046.6 | $ 3,525.1
Percent of total revenue |  |  |  |  |  |  |  |  | 100.00% | 100.00% | 100.00%
Total High-Value Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 86.00% | 84.00% | 82.00%
Nickel-based alloys and specialty alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 32.00% | 30.00% | 28.00%
Precision forgings, castings and components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 18.00% | 20.00% | 19.00%
Titanium and titanium-based alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 18.00% | 17.00% | 17.00%
Precision rolled strip products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 12.00% | 12.00% | 12.00%
Zirconium and related alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 6.00% | 5.00% | 6.00%
Standard stainless products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 14.00% | 16.00% | 18.00%
United States |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 2,454.6 | $ 2,348.1 | $ 2,070.6
China |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 355.6 | 320.0 | 265.6
Germany |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 219.3 | 247.2 | 217.1
United Kingdom |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 173.8 | 242.1 | 231.6
France |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 155.5 | 183.6 | 165.6
Japan |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 147.7 | 214.9 | 131.7
Rest of World |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 616.0 | 490.7 | 442.9
Aerospace & Defense |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 2,130.4 | 1,965.5 | 1,718.1
Energy |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 796.9 | 780.7 | 610.4
Automotive |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 296.6 | 323.4 | 273.7
Food Equipment & Appliances |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 205.8 | 244.9 | 226.0
Construction/Mining |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 195.0 | 226.0 | 192.9
Medical |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 172.4 | 183.1 | 183.0
Electronics/Computers/Communications |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 163.2 | 156.9 | 151.6
Other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 162.2 | 166.1 | 169.4
Operating Segments |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 4,446.4 | 4,341.6 | 3,758.0
Operating Segments | High Performance Materials & Components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 2,054.2 | $ 2,039.2 | $ 1,751.1
Percent of total revenue |  |  |  |  |  |  |  |  | 100.00% | 100.00% | 100.00%
Operating Segments | High Performance Materials & Components | Total High-Value Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 100.00% | 100.00% | 100.00%
Operating Segments | High Performance Materials & Components | Nickel-based alloys and specialty alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 38.00% | 37.00% | 37.00%
Operating Segments | High Performance Materials & Components | Precision forgings, castings and components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 36.00% | 40.00% | 38.00%
Operating Segments | High Performance Materials & Components | Titanium and titanium-based alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 26.00% | 23.00% | 25.00%
Operating Segments | High Performance Materials & Components | Precision rolled strip products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | High Performance Materials & Components | Zirconium and related alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | High Performance Materials & Components | Standard stainless products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | High Performance Materials & Components | United States |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 1,042.6 | $ 983.6 | $ 874.3
Operating Segments | High Performance Materials & Components | China |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 93.9 | 71.2 | 44.3
Operating Segments | High Performance Materials & Components | Germany |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 147.2 | 159.0 | 131.9
Operating Segments | High Performance Materials & Components | United Kingdom |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 156.7 | 225.6 | 200.8
Operating Segments | High Performance Materials & Components | France |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 132.7 | 146.3 | 143.3
Operating Segments | High Performance Materials & Components | Japan |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 95.0 | 128.1 | 88.5
Operating Segments | High Performance Materials & Components | Rest of World |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 310.4 | 249.3 | 221.7
Operating Segments | High Performance Materials & Components | Aerospace & Defense |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 1,624.1 | 1,562.9 | 1,377.0
Operating Segments | High Performance Materials & Components | Energy |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 153.6 | 133.9 | 119.7
Operating Segments | High Performance Materials & Components | Automotive |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 10.5 | 9.5 | 8.8
Operating Segments | High Performance Materials & Components | Food Equipment & Appliances |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 0.3 | 0.4 | 0.4
Operating Segments | High Performance Materials & Components | Construction/Mining |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 42.5 | 72.7 | 51.2
Operating Segments | High Performance Materials & Components | Medical |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 85.4 | 106.0 | 81.1
Operating Segments | High Performance Materials & Components | Electronics/Computers/Communications |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 0.5 | 1.5 | 1.0
Operating Segments | High Performance Materials & Components | Other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 61.6 | 76.2 | 65.6
Operating Segments | Advanced Alloys & Solutions |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 2,392.2 | $ 2,302.4 | $ 2,006.9
Percent of total revenue |  |  |  |  |  |  |  |  | 100.00% | 100.00% | 100.00%
Operating Segments | Advanced Alloys & Solutions | Total High-Value Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 72.00% | 68.00% | 66.00%
Operating Segments | Advanced Alloys & Solutions | Nickel-based alloys and specialty alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 27.00% | 24.00% | 20.00%
Operating Segments | Advanced Alloys & Solutions | Precision forgings, castings and components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | Advanced Alloys & Solutions | Titanium and titanium-based alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 11.00% | 10.00% | 10.00%
Operating Segments | Advanced Alloys & Solutions | Precision rolled strip products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 23.00% | 23.00% | 24.00%
Operating Segments | Advanced Alloys & Solutions | Zirconium and related alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 11.00% | 11.00% | 12.00%
Operating Segments | Advanced Alloys & Solutions | Standard stainless products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 28.00% | 32.00% | 34.00%
Operating Segments | Advanced Alloys & Solutions | United States |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 1,412.0 | $ 1,364.5 | $ 1,196.3
Operating Segments | Advanced Alloys & Solutions | China |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 261.7 | 248.8 | 221.3
Operating Segments | Advanced Alloys & Solutions | Germany |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 72.1 | 88.2 | 85.2
Operating Segments | Advanced Alloys & Solutions | United Kingdom |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 17.1 | 16.5 | 30.8
Operating Segments | Advanced Alloys & Solutions | France |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 22.8 | 37.3 | 22.3
Operating Segments | Advanced Alloys & Solutions | Japan |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 52.7 | 86.8 | 43.2
Operating Segments | Advanced Alloys & Solutions | Rest of World |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 305.6 | 241.4 | 221.2
Operating Segments | Advanced Alloys & Solutions | Aerospace & Defense |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 506.3 | 402.6 | 341.1
Operating Segments | Advanced Alloys & Solutions | Energy |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 643.3 | 646.8 | 490.7
Operating Segments | Advanced Alloys & Solutions | Automotive |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 286.1 | 313.9 | 264.9
Operating Segments | Advanced Alloys & Solutions | Food Equipment & Appliances |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 205.5 | 244.5 | 225.6
Operating Segments | Advanced Alloys & Solutions | Construction/Mining |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 152.5 | 153.3 | 141.7
Operating Segments | Advanced Alloys & Solutions | Medical |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 87.0 | 77.1 | 101.9
Operating Segments | Advanced Alloys & Solutions | Electronics/Computers/Communications |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 162.7 | 155.4 | 150.6
Operating Segments | Advanced Alloys & Solutions | Other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 100.6 | 89.9 | 103.8
External Customers | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 4,122.5 | 4,046.6 | 3,525.1
External Customers | Operating Segments | High Performance Materials & Components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 1,978.5 | 1,963.1 | 1,704.8
External Customers | Operating Segments | Advanced Alloys & Solutions |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 2,144.0 | $ 2,083.5 | $ 1,820.3

X
- Definition Revenue from Contract with Customer, Excluding Assessed Tax, Percentage of Revenue + References No definition available. + Details
Name: | ati_RevenuefromContractwithCustomerExcludingAssessedTaxPercentageofRevenue
Namespace Prefix: | ati_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045 + Details
Name: | us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_ProductOrServiceAxis=ati_HighValueProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=ati_NickelbasedAlloysandSpecialtyAlloysMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=ati_PrecisionForgingsCastingandComponentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=ati_TitaniumandTitaniumbasedAlloysMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=ati_PrecisionrolledstripproductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=ati_ZirconiumandRelatedAlloysMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=ati_StandardProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_CN
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_DE
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_GB
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_FR
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_JP
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=ati_RestOfWorldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_AerospaceandDefenseMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_EnergyMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_AutomotiveMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_FoodEquipmentandAppliancesMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_ConstructionMiningMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_MedicalMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_ElectronicDevicesMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContractWithCustomerSalesChannelAxis=ati_OtherMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ati_HighPerformanceMaterialsComponentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ati_AdvancedAlloysSolutionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=ati_ExternalCustomersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |