Segment Information, Geographic and Product Data - Schedule of Results of Operation, Depreciation and Amortization, Capital Expenditures and Total Assets by Reportable Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Consolidated net sales	$ 2,759.7	$ 2,550.3	$ 1,836.3
Consolidated operating income (loss)	323.1	133.1	(24.9)
Consolidated depreciation and amortization	134.6	131.0	131.4
Consolidated capital expenditures	96.6	82.3	91.3
Consolidated total assets	3,291.7	3,053.9
Corporate
Segment Reporting Information [Line Items]
Consolidated operating income (loss)	(123.0)	(75.5)	(52.8)
Consolidated depreciation and amortization	5.0	5.4	5.5
Consolidated capital expenditures	3.4	2.0	3.0
Consolidated total assets	334.8	159.0
Intersegment
Segment Reporting Information [Line Items]
Consolidated net sales	(95.1)	(97.0)	(73.8)
Consolidated operating income (loss)	1.6	(2.3)	0.2
Consolidated total assets	(16.8)	(17.9)
Specialty Alloys Operations | Operating
Segment Reporting Information [Line Items]
Consolidated net sales	2,443.8	2,213.6	1,565.6
Consolidated operating income (loss)	408.5	179.1	9.6
Consolidated depreciation and amortization	113.3	110.0	110.1
Consolidated capital expenditures	80.0	70.2	77.5
Consolidated total assets	2,542.2	2,461.2
Performance Engineered Products | Operating
Segment Reporting Information [Line Items]
Consolidated net sales	411.0	433.7	344.5
Consolidated operating income (loss)	36.0	31.8	18.1
Consolidated depreciation and amortization	16.3	15.6	15.8
Consolidated capital expenditures	13.2	10.1	$ 10.8
Consolidated total assets	$ 431.5	$ 451.6