Revenue - Summary of Revenues by End-Use Markets and Geography (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Total net sales	$ 676.9	$ 624.2	$ 1,394.5	$ 1,276.1
Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(19.6)	(20.9)	(47.9)	(40.7)
United States
Disaggregation of Revenue [Line Items]
Total net sales	419.2	374.0	840.3	767.4
United States | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(5.5)	(6.2)	(16.4)	(11.4)
Europe
Disaggregation of Revenue [Line Items]
Total net sales	105.3	106.5	245.7	213.9
Europe | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(4.2)	(4.0)	(9.9)	(8.3)
Asia Pacific
Disaggregation of Revenue [Line Items]
Total net sales	81.3	83.0	175.7	186.1
Asia Pacific | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(9.9)	(10.8)	(21.6)	(20.8)
Mexico
Disaggregation of Revenue [Line Items]
Total net sales	42.5	34.6	79.4	58.8
Mexico | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	(0.1)	(0.1)	0.0
Canada
Disaggregation of Revenue [Line Items]
Total net sales	14.5	14.1	28.9	27.8
Canada | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	0.1	0.0
Other
Disaggregation of Revenue [Line Items]
Total net sales	14.1	12.0	24.5	22.1
Other | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.2	0.0	(0.2)
Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total net sales	413.4	321.0	850.8	673.5
Aerospace and Defense | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(3.8)	(6.8)	(8.4)	(11.5)
Medical
Disaggregation of Revenue [Line Items]
Total net sales	86.3	87.7	173.2	167.6
Medical | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(13.3)	(10.2)	(29.4)	(21.4)
Energy
Disaggregation of Revenue [Line Items]
Total net sales	43.5	52.1	96.0	96.8
Energy | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	0.0	0.1
Transportation
Disaggregation of Revenue [Line Items]
Total net sales	28.5	37.2	56.8	79.2
Transportation | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(0.2)	0.0	(0.1)	0.0
Industrial and Consumer
Disaggregation of Revenue [Line Items]
Total net sales	85.2	104.3	176.4	209.4
Industrial and Consumer | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(2.3)	(3.8)	(10.0)	(7.8)
Distribution
Disaggregation of Revenue [Line Items]
Total net sales	20.0	21.9	41.3	49.6
Distribution | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	(0.1)	0.0	(0.1)
Specialty Alloys Operations | Operating
Disaggregation of Revenue [Line Items]
Total net sales	601.5	549.4	1,246.6	1,119.4
Specialty Alloys Operations | United States | Operating
Disaggregation of Revenue [Line Items]
Total net sales	367.0	326.3	740.7	666.8
Specialty Alloys Operations | Europe | Operating
Disaggregation of Revenue [Line Items]
Total net sales	93.4	91.9	223.2	186.8
Specialty Alloys Operations | Asia Pacific | Operating
Disaggregation of Revenue [Line Items]
Total net sales	80.7	82.3	175.1	185.0
Specialty Alloys Operations | Mexico | Operating
Disaggregation of Revenue [Line Items]
Total net sales	36.0	26.4	65.1	40.8
Specialty Alloys Operations | Canada | Operating
Disaggregation of Revenue [Line Items]
Total net sales	12.4	11.7	22.9	20.9
Specialty Alloys Operations | Other | Operating
Disaggregation of Revenue [Line Items]
Total net sales	12.0	10.8	19.6	19.1
Specialty Alloys Operations | Aerospace and Defense | Operating
Disaggregation of Revenue [Line Items]
Total net sales	393.0	302.1	810.9	634.1
Specialty Alloys Operations | Medical | Operating
Disaggregation of Revenue [Line Items]
Total net sales	57.6	65.5	118.8	120.9
Specialty Alloys Operations | Energy | Operating
Disaggregation of Revenue [Line Items]
Total net sales	41.6	48.4	93.2	91.5
Specialty Alloys Operations | Transportation | Operating
Disaggregation of Revenue [Line Items]
Total net sales	26.9	34.9	53.2	75.0
Specialty Alloys Operations | Industrial and Consumer | Operating
Disaggregation of Revenue [Line Items]
Total net sales	82.4	98.5	170.5	197.9
Specialty Alloys Operations | Distribution | Operating
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	0.0	0.0
Performance Engineered Products | Operating
Disaggregation of Revenue [Line Items]
Total net sales	95.0	95.7	195.8	197.4
Performance Engineered Products | United States | Operating
Disaggregation of Revenue [Line Items]
Total net sales	57.7	53.9	116.0	112.0
Performance Engineered Products | Europe | Operating
Disaggregation of Revenue [Line Items]
Total net sales	16.1	18.6	32.4	35.4
Performance Engineered Products | Asia Pacific | Operating
Disaggregation of Revenue [Line Items]
Total net sales	10.5	11.5	22.2	21.9
Performance Engineered Products | Mexico | Operating
Disaggregation of Revenue [Line Items]
Total net sales	6.5	8.3	14.4	18.0
Performance Engineered Products | Canada | Operating
Disaggregation of Revenue [Line Items]
Total net sales	2.1	2.4	5.9	6.9
Performance Engineered Products | Other | Operating
Disaggregation of Revenue [Line Items]
Total net sales	2.1	1.0	4.9	3.2
Performance Engineered Products | Aerospace and Defense | Operating
Disaggregation of Revenue [Line Items]
Total net sales	24.2	25.7	48.3	50.9
Performance Engineered Products | Medical | Operating
Disaggregation of Revenue [Line Items]
Total net sales	42.0	32.4	83.8	68.1
Performance Engineered Products | Energy | Operating
Disaggregation of Revenue [Line Items]
Total net sales	1.9	3.7	2.8	5.2
Performance Engineered Products | Transportation | Operating
Disaggregation of Revenue [Line Items]
Total net sales	1.8	2.3	3.7	4.2
Performance Engineered Products | Industrial and Consumer | Operating
Disaggregation of Revenue [Line Items]
Total net sales	5.1	9.6	15.9	19.3
Performance Engineered Products | Distribution | Operating
Disaggregation of Revenue [Line Items]
Total net sales	$ 20.0	$ 22.0	$ 41.3	$ 49.7