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Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue | $ 1,037.9 | $ 1,020.2 | $ 1,009.5 | $ 979.0 | $ 909.9 | $ 869.1 | $ 880.2 | $ 865.9 | $ 4,046.6 | $ 3,525.1 | $ 3,134.6
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% | 87.00%
Nickel-based alloys and specialty alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 30.00% | 28.00% | 28.00%
Precision forgings, castings and components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 20.00% | 19.00% | 18.00%
Titanium and titanium-based alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 17.00% | 17.00% | 20.00%
Precision and engineered strip |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 14.00% | 14.00% | 13.00%
Zirconium and related alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 5.00% | 6.00% | 8.00%
Total Standard Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 14.00% | 16.00% | 13.00%
Stainless steel sheet |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 8.00% | 9.00% | 7.00%
Specialty stainless sheet |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 4.00% | 5.00% | 4.00%
Stainless steel plate and other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 2.00% | 2.00% | 2.00%
United States |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 2,348.1 | $ 2,070.6 | $ 1,857.5
China |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 320.0 | 265.6 | 214.1
Germany |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 247.2 | 217.1 | 177.7
United Kingdom |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 242.1 | 231.6 | 183.8
Japan |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 214.9 | 131.7 | 151.9
France |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 183.6 | 165.6 | 142.6
Rest of World |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 490.7 | 442.9 | 407.0
Aerospace & Defense |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 1,965.5 | 1,718.1 | 1,590.4
Oil & Gas |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 546.2 | 418.2 | 280.8
Automotive |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 323.4 | 273.7 | 232.8
Food Equipment & Appliances |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 244.9 | 226.0 | 172.2
Electrical Energy |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 234.5 | 192.2 | 232.6
Construction/Mining |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 226.0 | 192.9 | 160.6
Medical |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 183.1 | 183.0 | 195.8
Electronics/Computers/Communications |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 156.9 | 151.6 | 109.7
Other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 166.1 | 169.4 | 159.7
Operating Segments |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 4,212.6 | 3,654.5 | 3,240.3
Operating Segments | High Performance Materials & Components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 2,413.6 | $ 2,127.0 | $ 1,979.5
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 |  |  |  |  |  |  |  |  | 31.00% | 31.00% | 29.00%
Operating Segments | High Performance Materials & Components | Precision forgings, castings and components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 34.00% | 32.00% | 29.00%
Operating Segments | High Performance Materials & Components | Titanium and titanium-based alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 25.00% | 26.00% | 29.00%
Operating Segments | High Performance Materials & Components | Precision and engineered strip |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  | 10.00% | 11.00% | 13.00%
Operating Segments | High Performance Materials & Components | Total Standard Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | High Performance Materials & Components | Stainless steel sheet |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | High Performance Materials & Components | Specialty stainless sheet |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | High Performance Materials & Components | Stainless steel plate and other |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  |  | $ 1,214.1 | $ 1,096.5 | $ 1,057.3
Operating Segments | High Performance Materials & Components | China |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 83.1 | 51.1 | 57.8
Operating Segments | High Performance Materials & Components | Germany |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 192.7 | 170.5 | 137.4
Operating Segments | High Performance Materials & Components | United Kingdom |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 232.4 | 220.9 | 171.1
Operating Segments | High Performance Materials & Components | Japan |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 136.5 | 95.2 | 113.4
Operating Segments | High Performance Materials & Components | France |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 172.7 | 157.8 | 134.9
Operating Segments | High Performance Materials & Components | Rest of World |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 302.7 | 275.4 | 258.5
Operating Segments | High Performance Materials & Components | Aerospace & Defense |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 1,771.3 | 1,568.9 | 1,439.2
Operating Segments | High Performance Materials & Components | Oil & Gas |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 74.9 | 63.9 | 46.5
Operating Segments | High Performance Materials & Components | Automotive |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 9.5 | 8.8 | 7.6
Operating Segments | High Performance Materials & Components | Food Equipment & Appliances |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 0.4 | 1.1 | 1.8
Operating Segments | High Performance Materials & Components | Electrical Energy |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 131.4 | 113.1 | 129.1
Operating Segments | High Performance Materials & Components | Construction/Mining |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 72.8 | 51.1 | 36.7
Operating Segments | High Performance Materials & Components | Medical |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 168.5 | 170.4 | 185.3
Operating Segments | High Performance Materials & Components | Electronics/Computers/Communications |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 7.9 | 4.4 | 3.4
Operating Segments | High Performance Materials & Components | Other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 97.5 | 85.7 | 80.8
Operating Segments | Flat Rolled Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 1,799.0 | $ 1,527.5 | $ 1,260.8
Percent of total revenue |  |  |  |  |  |  |  |  | 100.00% | 100.00% | 100.00%
Operating Segments | Flat Rolled Products | Total High-Value Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 66.00% | 63.00% | 65.00%
Operating Segments | Flat Rolled Products | Nickel-based alloys and specialty alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 28.00% | 24.00% | 25.00%
Operating Segments | Flat Rolled Products | Precision forgings, castings and components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | Flat Rolled Products | Titanium and titanium-based alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 5.00% | 5.00% | 4.00%
Operating Segments | Flat Rolled Products | Precision and engineered strip |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 33.00% | 34.00% | 36.00%
Operating Segments | Flat Rolled Products | Zirconium and related alloys |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 0.00% | 0.00% | 0.00%
Operating Segments | Flat Rolled Products | Total Standard Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 34.00% | 37.00% | 35.00%
Operating Segments | Flat Rolled Products | Stainless steel sheet |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 20.00% | 21.00% | 19.00%
Operating Segments | Flat Rolled Products | Specialty stainless sheet |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 10.00% | 12.00% | 11.00%
Operating Segments | Flat Rolled Products | Stainless steel plate and other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percent of total revenue |  |  |  |  |  |  |  |  | 4.00% | 4.00% | 5.00%
Operating Segments | Flat Rolled Products | United States |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 1,134.0 | $ 974.1 | $ 800.2
Operating Segments | Flat Rolled Products | China |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 236.9 | 214.5 | 156.3
Operating Segments | Flat Rolled Products | Germany |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 54.5 | 46.6 | 40.3
Operating Segments | Flat Rolled Products | United Kingdom |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 9.7 | 10.7 | 12.7
Operating Segments | Flat Rolled Products | Japan |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 78.4 | 36.5 | 38.5
Operating Segments | Flat Rolled Products | France |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 10.9 | 7.8 | 7.7
Operating Segments | Flat Rolled Products | Rest of World |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 188.0 | 167.5 | 148.5
Operating Segments | Flat Rolled Products | Aerospace & Defense |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 194.2 | 149.2 | 151.2
Operating Segments | Flat Rolled Products | Oil & Gas |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 471.3 | 354.3 | 234.3
Operating Segments | Flat Rolled Products | Automotive |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 313.9 | 264.9 | 225.2
Operating Segments | Flat Rolled Products | Food Equipment & Appliances |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 244.5 | 224.9 | 170.4
Operating Segments | Flat Rolled Products | Electrical Energy |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 103.1 | 79.1 | 103.5
Operating Segments | Flat Rolled Products | Construction/Mining |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 153.2 | 141.8 | 123.9
Operating Segments | Flat Rolled Products | Medical |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 14.6 | 12.6 | 10.5
Operating Segments | Flat Rolled Products | Electronics/Computers/Communications |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 149.0 | 147.2 | 106.3
Operating Segments | Flat Rolled Products | Other |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 68.6 | 83.7 | 78.9
External Customers | Operating Segments |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 4,046.6 | 3,525.1 | 3,134.6
External Customers | Operating Segments | High Performance Materials & Components |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 2,334.2 | 2,067.4 | 1,930.4
External Customers | Operating Segments | Flat Rolled Products |  |  |  |  |  |  |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 1,712.4 | $ 1,457.7 | $ 1,204.2

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