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		6 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Jun. 30, 2021
Net Sales:
Consolidated net sales	$ 396.0	$ 348.8	$ 783.6	$ 702.1
Operating (Loss) Income:
Consolidated operating loss	(31.5)	(89.0)	(50.6)	(137.8)
Depreciation and Amortization:
Consolidated depreciation and amortization	32.8	28.6	65.3	59.6
Capital Expenditures:
Consolidated capital expenditures	19.1	26.6	33.4	59.9
Total Assets:
Consolidated total assets	2,879.9		2,879.9		$ 2,971.2
Operating | Specialty Alloys Operations
Net Sales:
Consolidated net sales	330.8	300.4	662.8	601.1
Operating (Loss) Income:
Consolidated operating loss	(20.3)	(11.6)	(26.2)	(30.2)
Depreciation and Amortization:
Consolidated depreciation and amortization	27.4	23.3	54.6	46.5
Capital Expenditures:
Consolidated capital expenditures	16.6	15.7	28.7	37.4
Total Assets:
Consolidated total assets	2,222.3		2,222.3		2,150.1
Operating | Performance Engineered Products
Net Sales:
Consolidated net sales	85.7	54.8	160.3	116.7
Operating (Loss) Income:
Consolidated operating loss	3.0	(7.2)	3.6	(10.9)
Depreciation and Amortization:
Consolidated depreciation and amortization	4.0	4.2	7.9	10.3
Capital Expenditures:
Consolidated capital expenditures	2.0	1.1	3.2	3.2
Total Assets:
Consolidated total assets	419.6		419.6		418.5
Intersegment
Net Sales:
Consolidated net sales	(20.5)	(6.4)	(39.5)	(15.7)
Operating (Loss) Income:
Consolidated operating loss	0.3	0.4	0.6	0.4
Depreciation and Amortization:
Consolidated depreciation and amortization	0.0	0.1	0.0	0.1
Total Assets:
Consolidated total assets	4.1		4.1		0.4
Corporate
Operating (Loss) Income:
Consolidated operating loss	(14.5)	(70.6)	(28.6)	(97.1)
Depreciation and Amortization:
Consolidated depreciation and amortization	1.4	1.0	2.8	2.7
Capital Expenditures:
Consolidated capital expenditures	0.5	$ 9.8	1.5	$ 19.3
Total Assets:
Consolidated total assets	$ 233.9		$ 233.9		$ 402.2