Business Segments - Schedule of Results of Operation, Depreciation and Amortization, Capital Expenditures and Total Assets by Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Jun. 30, 2024
Net Sales
Total net sales	$ 727.0	$ 684.9	$ 2,121.5	$ 1,961.1
Operating Income (Loss)
Consolidated operating income	137.8	75.9	370.4	214.8
Depreciation and Amortization
Consolidated depreciation and amortization	35.4	34.1	103.6	100.8
Capital Expenditures
Consolidated capital expenditures	40.2	21.6	96.3	68.9
Total Assets
Consolidated total assets	3,361.8		3,361.8		$ 3,291.7
Operating | Specialty Alloys Operations
Net Sales
Total net sales	642.9	608.5	1,889.5	1,728.0
Operating Income (Loss)
Consolidated operating income	151.4	103.5	421.5	267.6
Depreciation and Amortization
Consolidated depreciation and amortization	29.8	28.8	87.2	85.0
Capital Expenditures
Consolidated capital expenditures	36.2	17.6	81.9	56.6
Total Assets
Consolidated total assets	2,671.7		2,671.7		2,542.2
Operating | Performance Engineered Products
Net Sales
Total net sales	104.9	102.4	300.8	299.9
Operating Income (Loss)
Consolidated operating income	10.9	9.2	25.3	25.4
Depreciation and Amortization
Consolidated depreciation and amortization	4.2	4.1	12.2	12.1
Capital Expenditures
Consolidated capital expenditures	2.8	3.2	12.5	9.4
Total Assets
Consolidated total assets	427.2		427.2		431.5
Corporate
Operating Income (Loss)
Consolidated operating income	(24.4)	(37.1)	(76.0)	(79.1)
Depreciation and Amortization
Consolidated depreciation and amortization	1.4	1.2	4.2	3.7
Capital Expenditures
Consolidated capital expenditures	1.2	0.8	1.9	2.9
Total Assets
Consolidated total assets	265.5		265.5		334.8
Intersegment
Net Sales
Total net sales	(20.8)	(26.0)	(68.8)	(66.8)
Operating Income (Loss)
Consolidated operating income	(0.1)	$ 0.3	(0.4)	$ 0.9
Total Assets
Consolidated total assets	$ (2.6)		$ (2.6)		$ (16.8)