Segment Information (Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Net sales:
Net sales	$ 782.0	$ 732.5	$ 1,527.2	$ 1,428.1
Net sales, percentage change	6.80%		6.90%
Operating income:
Operating income	$ 131.9	111.5	$ 229.2	199.9
Total segment operating profit, percentage change	18.30%		14.70%
Corporate, Non-Segment
Operating income:
Operating income	$ (16.3)	(13.8)	$ (34.4)	(26.7)
Total segment operating profit, percentage change	18.10%		28.80%
Intersegment Eliminations
Net sales:
Net sales	$ 4.0	5.5	$ 10.4	10.7
Instrumentation
Net sales:
Net sales	264.1	262.6	520.6	501.6
Instrumentation | Operating Segments
Net sales:
Net sales	$ 264.1	262.6	$ 520.6	501.6
Net sales, percentage change	0.60%		3.80%
Operating income:
Operating income	$ 49.0	40.9	$ 88.9	68.7
Total segment operating profit, percentage change	19.80%		29.40%
Digital Imaging
Net sales:
Net sales	$ 251.3	225.3	$ 486.6	436.3
Digital Imaging | Operating Segments
Net sales:
Net sales	$ 251.3	225.3	$ 486.6	436.3
Net sales, percentage change	11.50%		11.50%
Operating income:
Operating income	$ 52.5	43.3	$ 89.5	77.9
Total segment operating profit, percentage change	21.20%		14.90%
Aerospace and Defense Electronics
Net sales:
Net sales	$ 191.0	173.5	$ 371.4	347.1
Aerospace and Defense Electronics | Operating Segments
Net sales:
Net sales	$ 191.0	173.5	$ 371.4	347.1
Net sales, percentage change	10.10%		7.00%
Operating income:
Operating income	$ 39.4	33.7	$ 73.2	65.4
Total segment operating profit, percentage change	16.90%		11.90%
Engineered Systems
Net sales:
Net sales	$ 75.6	71.1	$ 148.6	143.1
Engineered Systems | Operating Segments
Net sales:
Net sales	$ 75.6	71.1	$ 148.6	143.1
Net sales, percentage change	6.30%		3.80%
Operating income:
Operating income	$ 7.3	$ 7.4	$ 12.0	$ 14.6
Total segment operating profit, percentage change	(1.40%)		(17.80%)