Segment Information (Reconciliation) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) product_line	Apr. 01, 2018 USD ($)
Net sales:
Net sales	$ 745.2	$ 695.6
Net sales, percentage change	7.10%
Operating income:
Operating income	$ 97.3	88.4
Total segment operating profit, percentage change	10.10%
Corporate, Non-Segment
Operating income:
Operating income	$ (18.1)	(12.9)
Total segment operating profit, percentage change	40.30%
Intersegment Eliminations
Net sales:
Net sales	$ 6.4	5.2
Instrumentation
Segment Reporting Information [Line Items]
Number of Product Lines | product_line	3
Net sales:
Net sales	$ 256.5	239.0
Instrumentation | Operating Segments
Net sales:
Net sales	$ 256.5	239.0
Net sales, percentage change	7.30%
Operating income:
Operating income	$ 39.9	27.8
Total segment operating profit, percentage change	43.50%
Digital Imaging
Net sales:
Net sales	$ 235.3	211.0
Digital Imaging | Operating Segments
Net sales:
Net sales	$ 235.3	211.0
Net sales, percentage change	11.50%
Operating income:
Operating income	$ 37.0	34.6
Total segment operating profit, percentage change	6.90%
Aerospace and Defense Electronics
Segment Reporting Information [Line Items]
Number of Product Lines | product_line	1
Net sales:
Net sales	$ 180.4	173.6
Aerospace and Defense Electronics | Operating Segments
Net sales:
Net sales	$ 180.4	173.6
Net sales, percentage change	3.90%
Operating income:
Operating income	$ 33.8	31.7
Total segment operating profit, percentage change	6.60%
Engineered Systems
Net sales:
Net sales	$ 73.0	72.0
Engineered Systems | Operating Segments
Net sales:
Net sales	$ 73.0	72.0
Net sales, percentage change	1.40%
Operating income:
Operating income	$ 4.7	$ 7.2
Total segment operating profit, percentage change	(34.70%)