Goodwill and Other Intangible Assets, Net - Narrative (Details) $ in Millions	12 Months Ended
	Jun. 30, 2024 USD ($) reportingUnit	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 01, 2024
Goodwill [Line Items]
Number of reporting units | reportingUnit	2
Goodwill	$ 227.3	$ 241.4	$ 241.4
Goodwill impairment charge	14.1	0.0	0.0
Accumulated impairment losses	148.7	134.6	134.6
Amortization expense	6.5	6.8	6.9
Estimated annual amortization expense for 2025	5.7
Estimated annual amortization expense for 2026	5.7
Estimated annual amortization expense for 2027	3.8
Estimated annual amortization expense for 2028	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	$ 45.9	$ 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%