Revenue - Summary of Revenues by End-Use Markets and Geography (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Total net sales	$ 727.0	$ 684.9	$ 2,121.5	$ 1,961.1
Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(20.8)	(26.0)	(68.8)	(66.8)
United States
Disaggregation of Revenue [Line Items]
Total net sales	433.6	383.3	1,273.9	1,150.7
United States | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(6.8)	(8.1)	(23.3)	(19.9)
Europe
Disaggregation of Revenue [Line Items]
Total net sales	160.6	141.6	406.3	355.5
Europe | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(5.7)	(7.8)	(15.6)	(16.1)
Asia Pacific
Disaggregation of Revenue [Line Items]
Total net sales	79.8	94.7	255.5	280.7
Asia Pacific | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(8.2)	(10.0)	(29.8)	(30.9)
Mexico
Disaggregation of Revenue [Line Items]
Total net sales	19.6	29.3	99.1	88.1
Mexico | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(0.1)	(0.1)	0.1	0.0
Canada
Disaggregation of Revenue [Line Items]
Total net sales	19.3	21.3	48.1	49.1
Canada | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	0.0	0.0
Other
Disaggregation of Revenue [Line Items]
Total net sales	14.1	14.7	38.6	37.0
Other | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	(0.2)	0.1
Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total net sales	454.7	391.1	1,305.6	1,064.7
Aerospace and Defense | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(3.6)	(6.7)	(11.9)	(18.3)
Medical
Disaggregation of Revenue [Line Items]
Total net sales	85.0	99.6	258.1	267.2
Medical | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(14.5)	(13.1)	(43.9)	(34.5)
Energy
Disaggregation of Revenue [Line Items]
Total net sales	46.4	38.7	142.3	135.4
Energy | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.1	0.0	0.0	0.0
Transportation
Disaggregation of Revenue [Line Items]
Total net sales	28.1	34.4	85.0	113.7
Transportation | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	(0.4)	(0.1)	(0.3)
Industrial and Consumer
Disaggregation of Revenue [Line Items]
Total net sales	90.5	97.6	266.9	307.0
Industrial and Consumer | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	(2.8)	(5.8)	(12.8)	(13.6)
Distribution
Disaggregation of Revenue [Line Items]
Total net sales	22.3	23.5	63.6	73.1
Distribution | Intersegment
Disaggregation of Revenue [Line Items]
Total net sales	0.0	0.0	(0.1)	(0.1)
Specialty Alloys Operations | Operating
Disaggregation of Revenue [Line Items]
Total net sales	642.9	608.5	1,889.5	1,728.0
Specialty Alloys Operations | United States | Operating
Disaggregation of Revenue [Line Items]
Total net sales	375.6	335.4	1,116.2	1,002.4
Specialty Alloys Operations | Europe | Operating
Disaggregation of Revenue [Line Items]
Total net sales	146.7	127.0	369.9	313.8
Specialty Alloys Operations | Asia Pacific | Operating
Disaggregation of Revenue [Line Items]
Total net sales	79.6	94.3	254.7	279.3
Specialty Alloys Operations | Mexico | Operating
Disaggregation of Revenue [Line Items]
Total net sales	12.5	20.9	77.5	61.6
Specialty Alloys Operations | Canada | Operating
Disaggregation of Revenue [Line Items]
Total net sales	16.2	18.5	39.1	39.4
Specialty Alloys Operations | Other | Operating
Disaggregation of Revenue [Line Items]
Total net sales	12.3	12.4	32.1	31.5
Specialty Alloys Operations | Aerospace and Defense | Operating
Disaggregation of Revenue [Line Items]
Total net sales	428.8	367.3	1,239.6	1,001.5
Specialty Alloys Operations | Medical | Operating
Disaggregation of Revenue [Line Items]
Total net sales	58.0	77.7	176.8	198.6
Specialty Alloys Operations | Energy | Operating
Disaggregation of Revenue [Line Items]
Total net sales	44.3	37.5	137.5	129.0
Specialty Alloys Operations | Transportation | Operating
Disaggregation of Revenue [Line Items]
Total net sales	26.2	33.0	79.5	108.0
Specialty Alloys Operations | Industrial and Consumer | Operating
Disaggregation of Revenue [Line Items]
Total net sales	85.6	93.0	256.1	290.9
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	104.9	102.4	300.8	299.9
Performance Engineered Products | United States | Operating
Disaggregation of Revenue [Line Items]
Total net sales	64.8	56.0	181.0	168.2
Performance Engineered Products | Europe | Operating
Disaggregation of Revenue [Line Items]
Total net sales	19.6	22.4	52.0	57.8
Performance Engineered Products | Asia Pacific | Operating
Disaggregation of Revenue [Line Items]
Total net sales	8.4	10.4	30.6	32.3
Performance Engineered Products | Mexico | Operating
Disaggregation of Revenue [Line Items]
Total net sales	7.2	8.5	21.5	26.5
Performance Engineered Products | Canada | Operating
Disaggregation of Revenue [Line Items]
Total net sales	3.1	2.8	9.0	9.7
Performance Engineered Products | Other | Operating
Disaggregation of Revenue [Line Items]
Total net sales	1.8	2.3	6.7	5.4
Performance Engineered Products | Aerospace and Defense | Operating
Disaggregation of Revenue [Line Items]
Total net sales	29.5	30.5	77.9	81.5
Performance Engineered Products | Medical | Operating
Disaggregation of Revenue [Line Items]
Total net sales	41.5	35.0	125.2	103.1
Performance Engineered Products | Energy | Operating
Disaggregation of Revenue [Line Items]
Total net sales	2.0	1.2	4.8	6.4
Performance Engineered Products | Transportation | Operating
Disaggregation of Revenue [Line Items]
Total net sales	1.9	1.8	5.6	6.0
Performance Engineered Products | Industrial and Consumer | Operating
Disaggregation of Revenue [Line Items]
Total net sales	7.7	10.4	23.6	29.7
Performance Engineered Products | Distribution | Operating
Disaggregation of Revenue [Line Items]
Total net sales	$ 22.3	$ 23.5	$ 63.7	$ 73.2