Goodwill and Other Intangible Assets, Net - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($)	Jun. 30, 2025 USD ($) reportingUnit	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 01, 2024
Goodwill [Line Items]
Number of reporting units | reportingUnit		2
Goodwill		$ 227.3	$ 227.3	$ 241.4
Goodwill impairment charge	$ 14.1	0.0	14.1	0.0
Accumulated impairment losses		148.7	148.7	134.6
Amortization expense		5.7	6.5	6.8
Estimated annual amortization expense for 2026		5.7
Estimated annual amortization expense for 2027		3.8
Estimated annual amortization expense for 2028		0.0
Estimated annual amortization expense for 2029		0.0
Estimated annual amortization expense for 2030		$ 0.0
Impairment of intangible assets			7.0
Special Alloy Operations Reporting Unit
Goodwill [Line Items]
Percentage of goodwill		86.00%
Reporting unit, percentage of fair value in excess of carrying amount					203.00%
Reporting unit, percentage of fair value in excess of carrying value if fair value reduced by one half percent					196.00%
Measurement Input, Terminal Growth Rate | Special Alloy Operations Reporting Unit
Goodwill [Line Items]
Reporting unit, long term growth rate reduction necessary to approximate net Book value					2.50%
Valuation Technique, Discounted Cash Flow | Measurement Input, Weighted Average Cost of Capital | Special Alloy Operations Reporting Unit
Goodwill [Line Items]
Goodwill, measurement input					9.50%
Valuation Technique, Discounted Cash Flow | Measurement Input, Terminal Growth Rate | Special Alloy Operations Reporting Unit
Goodwill [Line Items]
Goodwill, measurement input					0.50%
Performance Engineered Products
Goodwill [Line Items]
Goodwill		$ 31.8	31.8	$ 45.9
Goodwill impairment charge			$ 14.1
Performance Engineered Products | Dynamet
Goodwill [Line Items]
Goodwill		$ 31.8
Reporting unit, percentage of fair value in excess of carrying amount					144.00%
Reporting unit, percentage of fair value in excess of carrying value if fair value reduced by one half percent					140.00%
Performance Engineered Products | Measurement Input, Terminal Growth Rate | Dynamet
Goodwill [Line Items]
Reporting unit, long term growth rate reduction necessary to approximate net Book value					2.50%
Performance Engineered Products | Valuation Technique, Discounted Cash Flow | Measurement Input, Weighted Average Cost of Capital | Dynamet
Goodwill [Line Items]
Goodwill, measurement input					11.00%
Performance Engineered Products | Valuation Technique, Discounted Cash Flow | Measurement Input, Terminal Growth Rate | Dynamet
Goodwill [Line Items]
Goodwill, measurement input					0.50%