Goodwill and Other Intangible Assets, Net - Schedule of Goodwill (Details) - USD ($)	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Changes in the carrying amount of goodwill by reportable segment
Goodwill gross, beginning balance	$ 292,000,000	$ 292,100,000
Accumulated impairment losses, beginning balance	(47,200,000)	(34,700,000)
Total goodwill net, beginning balance	244,800,000	257,400,000
Impairment	0	(12,500,000)	$ 0
Other		(100,000)
Acquisition	18,600,000
Goodwill gross, ending balance	310,600,000	292,000,000	292,100,000
Accumulated impairment losses, ending balance	(47,200,000)	(47,200,000)	(34,700,000)
Total goodwill net, ending balance	263,400,000	244,800,000	257,400,000
Specialty Alloys Operations
Changes in the carrying amount of goodwill by reportable segment
Total goodwill net, beginning balance	195,500,000	195,500,000
Impairment		0
Other		0
Acquisition	0
Total goodwill net, ending balance	195,500,000	195,500,000	195,500,000
Performance Engineered Products
Changes in the carrying amount of goodwill by reportable segment
Total goodwill net, beginning balance	49,300,000	61,900,000
Impairment		(12,500,000)
Other		(100,000)
Acquisition	18,600,000
Total goodwill net, ending balance	$ 67,900,000	$ 49,300,000	$ 61,900,000