Business Segments (Details2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	$ 143.3	$ 151.1	$ 156.4
Capital expenditures	136.5	168.2	139.2
Operating Segments
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	143.3	151.1	156.4
Capital expenditures	136.5	168.2	139.2
Operating Segments | High Performance Materials & Components
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	78.1	84.6	90.6
Capital expenditures	83.1	119.9	71.7
Operating Segments | Corporate [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	3.1	3.0	2.9
Capital expenditures	7.5	0.9	3.0
Operating Segments | Advanced Alloys & Solutions [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	62.1	63.5	62.9
Capital expenditures	$ 45.9	$ 47.4	$ 64.5