Revenue - Summary of Revenues by End-Use Markets and Geography (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total net sales	$ 624.2	$ 579.1	$ 1,276.1	$ 1,102.0
Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(20.9)	(23.4)	(40.7)	(41.2)
United States
Disaggregation of Revenue [Line Items]
Total net sales	374.0	353.7	767.4	673.3
United States | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(6.2)	(10.3)	(11.4)	(17.6)
Europe
Disaggregation of Revenue [Line Items]
Total net sales	106.5	87.2	213.9	178.0
Europe | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(4.0)	(3.2)	(8.3)	(7.1)
Asia Pacific
Disaggregation of Revenue [Line Items]
Total net sales	83.0	79.2	186.1	137.3
Asia Pacific | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(10.8)	(9.8)	(20.8)	(16.4)
Mexico
Disaggregation of Revenue [Line Items]
Total net sales	34.6	32.2	58.8	65.2
Mexico | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(0.1)	0.0	0.0	0.0
Canada
Disaggregation of Revenue [Line Items]
Total net sales	14.1	15.4	27.8	27.1
Canada | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.1	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Total net sales	12.0	11.4	22.1	21.1
Other | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.2	(0.2)	(0.2)	(0.1)
Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total net sales	321.0	280.1	673.5	541.8
Aerospace and Defense | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(6.8)	(6.4)	(11.5)	(12.4)
Medical
Disaggregation of Revenue [Line Items]
Total net sales	87.7	73.7	167.6	132.9
Medical | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(10.2)	(8.7)	(21.4)	(14.9)
Transportation
Disaggregation of Revenue [Line Items]
Total net sales	37.2	41.4	79.2	78.3
Transportation | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	(0.3)	0.0	(0.4)
Energy
Disaggregation of Revenue [Line Items]
Total net sales	52.1	34.8	96.8	62.7
Energy | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	0.1	(0.1)
Industrial and Consumer
Disaggregation of Revenue [Line Items]
Total net sales	104.3	119.7	209.4	224.6
Industrial and Consumer | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(3.8)	(7.9)	(7.8)	(13.3)
Distribution
Disaggregation of Revenue [Line Items]
Total net sales	21.9	29.4	49.6	61.7
Distribution | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(0.1)	(0.1)	(0.1)	(0.1)
Specialty Alloys Operations
Disaggregation of Revenue [Line Items]
Total net sales	549.4	495.8	1,119.4	943.2
Specialty Alloys Operations | United States
Disaggregation of Revenue [Line Items]
Total net sales	326.3	303.0	666.8	574.3
Specialty Alloys Operations | Europe
Disaggregation of Revenue [Line Items]
Total net sales	91.9	71.0	186.8	149.9
Specialty Alloys Operations | Asia Pacific
Disaggregation of Revenue [Line Items]
Total net sales	82.3	79.0	185.0	136.6
Specialty Alloys Operations | Mexico
Disaggregation of Revenue [Line Items]
Total net sales	26.4	22.0	40.8	44.1
Specialty Alloys Operations | Canada
Disaggregation of Revenue [Line Items]
Total net sales	11.7	11.9	20.9	20.7
Specialty Alloys Operations | Other
Disaggregation of Revenue [Line Items]
Total net sales	10.8	8.9	19.1	17.6
Specialty Alloys Operations | Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total net sales	302.1	263.5	634.1	510.4
Specialty Alloys Operations | Medical
Disaggregation of Revenue [Line Items]
Total net sales	65.5	49.5	120.9	90.3
Specialty Alloys Operations | Transportation
Disaggregation of Revenue [Line Items]
Total net sales	34.9	40.1	75.0	76.0
Specialty Alloys Operations | Energy
Disaggregation of Revenue [Line Items]
Total net sales	48.4	32.1	91.5	58.7
Specialty Alloys Operations | Industrial and Consumer
Disaggregation of Revenue [Line Items]
Total net sales	98.5	110.6	197.9	207.8
Specialty Alloys Operations | Distribution
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	0.0	0.0
Performance Engineered Products
Disaggregation of Revenue [Line Items]
Total net sales	95.7	106.7	197.4	200.0
Performance Engineered Products | United States
Disaggregation of Revenue [Line Items]
Total net sales	53.9	61.0	112.0	116.6
Performance Engineered Products | Europe
Disaggregation of Revenue [Line Items]
Total net sales	18.6	19.4	35.4	35.2
Performance Engineered Products | Asia Pacific
Disaggregation of Revenue [Line Items]
Total net sales	11.5	10.0	21.9	17.1
Performance Engineered Products | Mexico
Disaggregation of Revenue [Line Items]
Total net sales	8.3	10.2	18.0	21.1
Performance Engineered Products | Canada
Disaggregation of Revenue [Line Items]
Total net sales	2.4	3.4	6.9	6.4
Performance Engineered Products | Other
Disaggregation of Revenue [Line Items]
Total net sales	1.0	2.7	3.2	3.6
Performance Engineered Products | Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total net sales	25.7	23.0	50.9	43.8
Performance Engineered Products | Medical
Disaggregation of Revenue [Line Items]
Total net sales	32.4	32.9	68.1	57.5
Performance Engineered Products | Transportation
Disaggregation of Revenue [Line Items]
Total net sales	2.3	1.6	4.2	2.7
Performance Engineered Products | Energy
Disaggregation of Revenue [Line Items]
Total net sales	3.7	2.7	5.2	4.1
Performance Engineered Products | Industrial and Consumer
Disaggregation of Revenue [Line Items]
Total net sales	9.6	17.0	19.3	30.1
Performance Engineered Products | Distribution
Disaggregation of Revenue [Line Items]
Total net sales	$ 22.0	$ 29.5	$ 49.7	$ 61.8