Operating Segments and Related Disclosures - Schedule of Selected Financial Information for Each Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net Sales:
Net sales	$ 545.3	$ 527.7	$ 1,598.3	$ 1,516.2
Reconciliation of segment performance to income before income taxes:
Segment performance	71.4	56.5	191.5	182.6
Interest expense	(4.9)	(7.2)	(15.1)	(23.0)
Interest income	0.2	0.5	1.5	4.7
Stock-based compensation	(0.5)	(5.5)	(10.6)	(13.2)
Income before income taxes	57.3	40.7	142.0	136.9
Operating Segments
Net Sales:
Net sales	545.3	527.7	1,598.3	1,516.2
Reconciliation of segment performance to income before income taxes:
Segment performance	73.5	61.3	210.5	190.6
Operating Segments | Aerospace and Defense
Net Sales:
Net sales	544.7	527.1	1,596.2	1,513.4
Segment Performance:
Aerospace and Defense	76.0	61.5	213.3	184.4
Environmental remediation provision adjustments	(2.2)	(1.6)	(3.2)	(1.7)
Retirement benefits, net	2.7	1.8	8.6	11.1
Unusual items	(2.9)	0.0	(7.5)	(1.8)
Reconciliation of segment performance to income before income taxes:
Segment performance	73.6	61.7	211.2	192.0
Unusual items	(2.9)	0.0	(7.5)	(1.8)
Operating Segments | Real Estate Segment
Net Sales:
Net sales	0.6	0.6	2.1	2.8
Reconciliation of segment performance to income before income taxes:
Segment performance	(0.1)	(0.4)	(0.7)	(1.4)
Segment Reconciling Items
Segment Performance:
Unusual items	(5.2)	0.0	(23.8)	0.0
Reconciliation of segment performance to income before income taxes:
Segment performance	73.5	61.3	210.5	190.6
Interest expense	(4.9)	(7.2)	(15.1)	(23.0)
Interest income	0.2	0.5	1.5	4.7
Stock-based compensation	(0.5)	(5.5)	(10.6)	(13.2)
Unusual items	(5.2)	0.0	(23.8)	0.0
Corporate, Non-Segment
Segment Performance:
Retirement benefits, net	(1.6)	(1.8)	(4.9)	(5.6)
Reconciliation of segment performance to income before income taxes:
Corporate and other	$ (4.2)	$ (6.6)	$ (15.6)	$ (16.6)