Segment Information - Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Net sales:
Net sales	$ 805.7	$ 784.6
Net sales, percentage change	2.70%
Operating income:
Operating income	$ 135.2	104.0
Total segment operating profit, percentage change	30.00%
Corporate expense
Operating income:
Operating income	$ (19.4)	(15.4)
Total segment operating profit, percentage change	26.00%
Inter-segment sales
Net sales:
Net sales	$ 4.2	6.9
Instrumentation
Net sales:
Net sales	286.5	285.1
Instrumentation | Operating segments
Net sales:
Net sales	$ 286.5	285.1
Net sales, percentage change	0.50%
Operating income:
Operating income	$ 59.4	50.8
Total segment operating profit, percentage change	16.90%
Digital Imaging
Net sales:
Net sales	$ 263.3	246.7
Digital Imaging | Operating segments
Net sales:
Net sales	$ 263.3	246.7
Net sales, percentage change	6.70%
Operating income:
Operating income	$ 52.0	43.8
Total segment operating profit, percentage change	18.70%
Aerospace and Defense Electronics
Net sales:
Net sales	$ 151.2	156.3
Aerospace and Defense Electronics | Operating segments
Net sales:
Net sales	$ 151.2	156.3
Net sales, percentage change	(3.30%)
Operating income:
Operating income	$ 28.3	13.4
Total segment operating profit, percentage change	111.20%
Engineered Systems
Net sales:
Net sales	$ 104.7	96.5
Engineered Systems | Operating segments
Net sales:
Net sales	$ 104.7	96.5
Net sales, percentage change	8.50%
Operating income:
Operating income	$ 14.9	$ 11.4
Total segment operating profit, percentage change	30.70%