Business Segments (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Sales	$ 1,038.1	$ 834.1
Segment EBITDA	152.8	143.4
Corporate expenses	(17.3)	(17.0)
Closed operations and other expense	(2.8)	(1.4)
Depreciation & amortization	(35.1)	(35.5)
Interest expense, net	(19.9)	(23.6)
Income (loss) from equity investments	(0.3)	0.4
Restructuring and other charges	(1.2)	(7.5)
Gain (loss) on asset sales and sale of businesses, net	0.0	(18.3)
Income before income taxes	76.5	40.1
Operating Segments
Segment Reporting Information [Line Items]
Sales	1,155.4	916.4
Depreciation & amortization	(35.1)	(35.5)
Operating Segments \| High Performance Materials & Components
Segment Reporting Information [Line Items]
Sales	529.6	380.8
Segment EBITDA	80.1	68.1
Depreciation & amortization	(17.4)	(17.9)
Operating Segments \| Advanced Alloys & Solutions
Segment Reporting Information [Line Items]
Sales	625.8	535.6
Segment EBITDA	72.7	75.3
Depreciation & amortization	(16.1)	(16.2)
Operating Segments \| Corporate Segment
Segment Reporting Information [Line Items]
Depreciation & amortization	(1.6)	(1.4)
Internal Customers \| Operating Segments
Segment Reporting Information [Line Items]
Sales	117.3	82.3
Internal Customers \| Operating Segments \| High Performance Materials & Components
Segment Reporting Information [Line Items]
Sales	58.5	39.2
Internal Customers \| Operating Segments \| Advanced Alloys & Solutions
Segment Reporting Information [Line Items]
Sales	58.8	43.1
External Customers \| Operating Segments
Segment Reporting Information [Line Items]
Sales	1,038.1	834.1
External Customers \| Operating Segments \| High Performance Materials & Components
Segment Reporting Information [Line Items]
Sales	471.1	341.6
External Customers \| Operating Segments \| Advanced Alloys & Solutions
Segment Reporting Information [Line Items]
Sales	$ 567.0	$ 492.5

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