Business Segments (Business Segments) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 29, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 30, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
Net sales:
Net Sales	$ 834.2	$ 802.2	$ 782.0	$ 745.2	$ 748.4	$ 725.3	$ 732.5	$ 695.6	$ 3,163.6	$ 2,901.8	$ 2,603.8
Operating income:
Total operating income	133.8	128.7	131.9	97.3	111.2	105.5	111.5	88.4	491.7	416.6	321.7
Depreciation and amortization:
Depreciation and amortization:									111.9	113.0	113.0
Instrumentation
Net sales:
Net Sales									1,105.1	1,021.2	953.9
Digital Imaging
Net sales:
Net Sales									992.9	875.3
Aerospace and Defense Electronics
Net sales:
Net Sales									690.1	640.2
Engineered Systems
Net sales:
Net Sales									375.5	365.1
Operating Segments
Restructuring Charges:
Restructuring charges									3.2	7.8	4.2
Net sales:
Net Sales									3,163.6	2,901.8	2,603.8
Operating income:
Total operating income									491.7	416.6	321.7
Depreciation and amortization:
Depreciation and amortization:									111.9	113.0	113.0
Capital expenditures:
Capital expenditures:									88.4	86.8	58.5
Identifiable assets:
Identifiable assets	4,579.8				3,809.3				4,579.8	3,809.3	3,846.4
Operating Segments | Instrumentation
Restructuring Charges:
Restructuring charges									1.5	5.6	2.1
Net sales:
Net Sales	301.6	282.9	264.1	256.5	263.4	256.2	262.6	239.0	1,105.1	1,021.2	953.9
Operating income:
Total operating income	59.5	52.0	49.0	39.9	43.0	35.7	40.9	27.8	200.4	147.4	126.0
Depreciation and amortization:
Depreciation and amortization:									35.9	37.0	38.2
Capital expenditures:
Capital expenditures:									18.9	14.8	13.7
Identifiable assets:
Identifiable assets	1,680.2				1,392.7				1,680.2	1,392.7	1,413.6
Operating Segments | Digital Imaging
Restructuring Charges:
Restructuring charges									1.1	0.7	0.0
Net sales:
Net Sales	268.1	244.0	248.4	232.4	223.3	220.7	223.0	208.3	992.9	875.3	710.4
Operating income:
Total operating income	47.1	41.2	51.6	36.6	36.3	42.3	43.1	33.8	176.5	155.5	110.2
Depreciation and amortization:
Depreciation and amortization:									48.5	50.8	49.6
Capital expenditures:
Capital expenditures:									45.2	35.8	23.4
Identifiable assets:
Identifiable assets	1,874.6				1,577.5				1,874.6	1,577.5	1,582.2
Operating Segments | Aerospace and Defense Electronics
Restructuring Charges:
Restructuring charges									0.5	1.3	2.1
Net sales:
Net Sales	170.4	177.1	176.0	166.6	166.0	160.3	157.5	156.4	690.1	640.2	591.2
Operating income:
Total operating income	32.8	39.5	38.6	32.5	35.4	33.0	32.6	30.8	143.4	131.8	113.0
Depreciation and amortization:
Depreciation and amortization:									14.3	13.8	14.0
Capital expenditures:
Capital expenditures:									19.0	18.7	9.3
Identifiable assets:
Identifiable assets	618.3				509.9				618.3	509.9	491.2
Operating Segments | Engineered Systems
Restructuring Charges:
Restructuring charges									0.1	0.2	0.0
Net sales:
Net Sales	94.1	98.2	93.5	89.7	95.7	88.1	89.4	91.9	375.5	365.1	348.3
Operating income:
Total operating income	10.5	10.6	9.0	6.4	10.7	9.6	8.7	8.9	36.5	37.9	35.5
Depreciation and amortization:
Depreciation and amortization:									6.0	4.3	4.6
Capital expenditures:
Capital expenditures:									3.6	13.6	7.4
Identifiable assets:
Identifiable assets	143.4				151.5				143.4	151.5	135.5
Corporate expense
Operating income:
Total operating income	(16.1)	$ (14.6)	$ (16.3)	$ (18.1)	(14.2)	$ (15.1)	$ (13.8)	$ (12.9)	(65.1)	(56.0)	(63.0)
Depreciation and amortization:
Depreciation and amortization:									7.2	7.1	6.6
Capital expenditures:
Capital expenditures:									1.7	3.9	4.7
Identifiable assets:
Identifiable assets	$ 263.3				$ 177.7				$ 263.3	$ 177.7	$ 223.9