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Business Segments (Details2) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Segment Reporting Other Significant Reconciling Item [Line Items] |  |  |
Depreciation and amortization | $ 156.4 | $ 160.8 | $ 170.3
Capital expenditures | 139.2 | 122.7 | 202.2
Operating Segments |  |  |
Segment Reporting Other Significant Reconciling Item [Line Items] |  |  |
Depreciation and amortization | 156.4 | 160.8 | 170.3
Capital expenditures | 139.2 | 122.7 | 202.2
Operating Segments | High Performance Materials & Components |  |  |
Segment Reporting Other Significant Reconciling Item [Line Items] |  |  |
Depreciation and amortization | 106.5 | 109.3 | 118.4
Capital expenditures | 79.8 | 62.7 | 89.9
Operating Segments | Flat Rolled Products |  |  |
Segment Reporting Other Significant Reconciling Item [Line Items] |  |  |
Depreciation and amortization | 47.0 | 45.6 | 48.8
Capital expenditures | 56.4 | 59.1 | 111.8
Operating Segments | Corporate [Member] |  |  |
Segment Reporting Other Significant Reconciling Item [Line Items] |  |  |
Depreciation and amortization | 2.9 | 5.9 | 3.1
Capital expenditures | $ 3.0 | $ 0.9 | $ 0.5

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