Operating Segments and Related Disclosures - Schedule of Selected Financial Information for Each Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net Sales:
Net sales	$ 512.4	$ 485.0	$ 988.5	$ 976.7
Segment Performance:
Unusual items	(1.8)	0.0	(1.8)	(0.3)
Reconciliation of segment performance to income before income taxes:
Segment performance	69.0	71.1	126.1	134.4
Interest expense	(7.4)	(9.2)	(15.8)	(18.2)
Interest income	1.0	4.0	4.2	8.0
Stock-based compensation	(5.3)	(10.2)	(7.7)	(15.5)
Income before income taxes	53.5	59.4	96.2	111.2
Operating Segments
Net Sales:
Net sales	512.4	485.0	988.5	976.7
Reconciliation of segment performance to income before income taxes:
Segment performance	72.1	82.8	129.3	153.0
Operating Segments | Aerospace and Defense
Net Sales:
Net sales	511.9	483.1	986.3	973.1
Segment Performance:
Operating profit	70.3	77.1	122.9	142.0
Environmental remediation provision adjustments	(0.6)	(0.4)	(0.1)	(0.7)
Retirement benefits, net	4.6	5.5	9.3	10.9
Unusual items	(1.8)	0.0	(1.8)	(0.3)
Reconciliation of segment performance to income before income taxes:
Segment performance	72.5	82.2	130.3	151.9
Operating Segments | Real Estate
Net Sales:
Net sales	0.5	1.9	2.2	3.6
Reconciliation of segment performance to income before income taxes:
Segment performance	(0.4)	0.6	(1.0)	1.1
Segment Reconciling Items
Reconciliation of segment performance to income before income taxes:
Interest expense	(7.4)	(9.2)	(15.8)	(18.2)
Interest income	1.0	4.0	4.2	8.0
Stock-based compensation	(5.3)	(10.2)	(7.7)	(15.5)
Corporate, Non-Segment
Segment Performance:
Retirement benefits, net	(1.8)	(1.8)	(3.8)	(3.6)
Reconciliation of segment performance to income before income taxes:
Corporate and other	$ (5.1)	$ (6.2)	$ (10.0)	$ (12.5)