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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

X

- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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X

- Definition

The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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- Definition

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+ References

No definition available.

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