Operating Segments and Related Disclosures - Schedule of Selected Financial Information for Each Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net Sales:
Net sales	$ 405.3	$ 356.9
Reconciliation of segment performance to income before income taxes:
Interest expense	(7.4)	(11.1)
Interest income	0.5	0.2
Stock-based compensation expense	(6.8)	(2.3)
Unusual items	(0.4)	(0.2)
Income before income taxes	9.2	8.6
Cash funding to tax-qualified defined benefit pension plan, recoverable in current year	37.0
Pension Benefits
Reconciliation of segment performance to income before income taxes:
Cash funding to tax-qualified defined benefit pension plan, recoverable in current year	9.3	6.9
Operating Segments
Segment Performance:
Segment performance	35.5	30.7
Reconciliation of segment performance to income before income taxes:
Segment performance	35.5	30.7
Operating Segments | Aerospace and Defense
Net Sales:
Net sales	403.7	355.3
Segment Performance:
Operating profit	38.7	36.0
Environmental remediation provision adjustments	(0.6)	(0.6)
Retirement benefit plan benefit (expense), net	(4.0)	(5.6)
Segment performance	34.7	29.9
Reconciliation of segment performance to income before income taxes:
Segment performance	34.7	29.9
Unusual items	0.6	0.1
Operating Segments | Real Estate
Net Sales:
Net sales	1.6	1.6
Segment Performance:
Segment performance	0.8	0.8
Reconciliation of segment performance to income before income taxes:
Segment performance	0.8	0.8
Segment Reconciling Items
Reconciliation of segment performance to income before income taxes:
Interest expense	(7.4)	(11.1)
Interest income	0.5	0.2
Stock-based compensation expense	(6.8)	(2.3)
Unusual items	(1.0)	(0.3)
Corporate, Non-Segment
Segment Performance:
Retirement benefit plan benefit (expense), net	(5.0)	(4.7)
Reconciliation of segment performance to income before income taxes:
Corporate and other expense, net	$ (6.6)	$ (3.9)