Segment Information (Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2017	Oct. 02, 2016	Oct. 01, 2017	Oct. 02, 2016
Net sales:
Net sales	$ 662.2	$ 526.8	$ 1,899.4	$ 1,597.0
Net sales, percentage change	25.70%		18.90%
Operating income(b):
Operating income	$ 92.9	68.8	$ 237.2	183.3
Total segment operating profit, percentage change	35.00%		29.40%
Corporate, Non-Segment
Operating income(b):
Operating income	$ (13.2)	(11.1)	$ (48.4)	(32.7)
Total segment operating profit, percentage change	18.90%		48.00%
Intersegment Eliminations
Net sales:
Net sales	$ 6.4	4.2	$ 17.8	16.2
Instrumentation | Operating Segments
Net sales:
Net sales	$ 232.5	208.3	$ 699.1	652.1
Net sales, percentage change	11.60%		7.20%
Operating income(b):
Operating income	$ 34.8	28.1	$ 96.0	79.6
Total segment operating profit, percentage change	23.80%		20.60%
Digital Imaging | Operating Segments
Net sales:
Net sales	$ 191.5	98.5	$ 493.8	287.8
Net sales, percentage change	94.40%		71.60%
Operating income(b):
Operating income	$ 31.9	11.7	$ 73.6	30.6
Total segment operating profit, percentage change	172.60%		140.50%
Aerospace and Defense Electronics | Operating Segments
Net sales:
Net sales	$ 165.1	153.5	$ 489.8	464.1
Net sales, percentage change	7.60%		5.50%
Operating income(b):
Operating income	$ 29.4	31.5	$ 88.0	83.6
Total segment operating profit, percentage change	(6.70%)		5.30%
Engineered Systems | Operating Segments
Net sales:
Net sales	$ 73.1	66.5	$ 216.7	193.0
Net sales, percentage change	9.90%		12.30%
Operating income(b):
Operating income	$ 10.0	$ 8.6	$ 28.0	$ 22.2
Total segment operating profit, percentage change	16.30%		26.10%
e2v
Operating income(b):
Operating income			$ 9.4
Acquisition related costs			28.1
e2v | Cost Of Sales And Sales General And Administrative Expenses
Operating income(b):
Acquisition related costs			19.8
e2v | Cost Of Sales And Sales General And Administrative Expenses | Corporate, Non-Segment
Operating income(b):
Acquisition related costs			10.4
e2v | Cost Of Sales And Sales General And Administrative Expenses | Digital Imaging
Operating income(b):
Acquisition related costs	$ 2.9		9.1
e2v | Cost Of Sales And Sales General And Administrative Expenses | Aerospace and Defense Electronics
Operating income(b):
Acquisition related costs			$ 0.3