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
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021
Net Sales:
Consolidated net sales	$ 387.6	$ 353.3
Operating (Loss) Income:
Consolidated operating (loss) income	(19.1)	(48.8)
Depreciation and Amortization:
Consolidated depreciation and amortization	32.5	30.9
Capital Expenditures:
Consolidated capital expenditures	14.4	33.3
Total Assets:
Consolidated total assets	2,959.9		$ 2,971.2
Operating | Specialty Alloys Operations
Net Sales:
Consolidated net sales	331.9	300.7
Operating (Loss) Income:
Consolidated operating (loss) income	(5.9)	(18.6)
Depreciation and Amortization:
Consolidated depreciation and amortization	27.2	23.2
Capital Expenditures:
Consolidated capital expenditures	12.1	21.8
Total Assets:
Consolidated total assets	2,209.8		2,150.1
Operating | Performance Engineered Products
Net Sales:
Consolidated net sales	74.6	61.8
Operating (Loss) Income:
Consolidated operating (loss) income	0.6	(3.6)
Depreciation and Amortization:
Consolidated depreciation and amortization	3.9	6.0
Capital Expenditures:
Consolidated capital expenditures	1.3	2.2
Total Assets:
Consolidated total assets	416.1		418.5
Intersegment
Net Sales:
Consolidated net sales	(18.9)	(9.2)
Operating (Loss) Income:
Consolidated operating (loss) income	0.4	0.0
Capital Expenditures:
Consolidated capital expenditures	0.0	(0.1)
Total Assets:
Consolidated total assets	2.3		0.4
Corporate
Operating (Loss) Income:
Consolidated operating (loss) income	(14.2)	(26.6)
Depreciation and Amortization:
Consolidated depreciation and amortization	1.4	1.7
Capital Expenditures:
Consolidated capital expenditures	1.0	$ 9.4
Total Assets:
Consolidated total assets	$ 331.7		$ 402.2