Business Segments - Summarized Financial Information by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Net sales	$ 733.7	$ 717.6
Cost of sales	517.3	541.3
Operating income	153.3	113.6
Interest expense, net	11.5	12.4
Other (income) expense, net	(3.0)	0.1
Income before income taxes	144.8	101.1
Intersegment
Segment Reporting Information [Line Items]
Net sales	(19.5)	(28.3)
Operating income	(0.2)	(0.2)
Operating
Segment Reporting Information [Line Items]
Net sales	753.2	745.9
Cost of sales	536.8	569.3
Other segment items	36.3	34.8
Operating income	180.1	141.8
Corporate
Segment Reporting Information [Line Items]
Operating income	(26.6)	(28.0)
Specialty Alloys Operations
Segment Reporting Information [Line Items]
Net sales	656.1	641.6
Specialty Alloys Operations | Intersegment
Segment Reporting Information [Line Items]
Net sales	(3.5)	(3.5)
Specialty Alloys Operations | Operating
Segment Reporting Information [Line Items]
Net sales	659.6	645.1
Cost of sales	458.0	481.5
Other segment items	30.9	29.1
Operating income	170.7	134.5
Performance Engineered Products
Segment Reporting Information [Line Items]
Net sales	77.6	76.0
Performance Engineered Products | Intersegment
Segment Reporting Information [Line Items]
Net sales	(16.0)	(24.8)
Performance Engineered Products | Operating
Segment Reporting Information [Line Items]
Net sales	93.6	100.8
Cost of sales	78.8	87.8
Other segment items	5.4	5.7
Operating income	$ 9.4	$ 7.3