Business Segments (Business Segments) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jan. 01, 2017	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Jan. 03, 2016	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Jan. 01, 2017	Jan. 03, 2016	Dec. 28, 2014
Net sales:
Net Sales	$ 552.9	$ 526.8	$ 539.7	$ 530.5	$ 600.0	$ 555.4	$ 577.7	$ 565.0	$ 2,149.9	$ 2,298.1	$ 2,394.0
Operating income:
Total operating income	70.5	68.8	53.6	60.9	76.0	69.5	68.9	67.3	253.8	281.7	294.5
Depreciation and amortization:
Depreciation and amortization:									87.3	90.3	94.3
Identifiable assets:
Prepaid pension assets	88.5				111.0				88.5	111.0
Instrumentation
Net sales:
Net Sales									876.7	1,051.1	1,115.5
Operating Segments
Restructuring Charges:
Restructuring charges									17.3	8.4	4.4
Net sales:
Net Sales									2,149.9	2,298.1	2,394.0
Operating income:
Total operating income									253.8	281.7	294.5
Depreciation and amortization:
Depreciation and amortization:									87.3	90.3	94.3
Capital expenditures:
Capital expenditures:									87.6	47.0	43.5
Identifiable assets:
Identifiable assets	2,774.4				2,717.1				2,774.4	2,717.1	2,862.2
Operating Segments | Instrumentation
Restructuring Charges:
Restructuring charges									10.6	3.9	1.0
Net sales:
Net Sales	224.6	208.3	220.1	223.7	266.3	243.2	271.3	270.3	876.7	1,051.1	1,115.5
Operating income:
Total operating income	30.2	28.1	20.1	31.4	44.6	38.6	45.7	42.1	109.8	171.0	181.6
Depreciation and amortization:
Depreciation and amortization:									37.3	41.2	41.1
Capital expenditures:
Capital expenditures:									50.9	20.9	17.0
Identifiable assets:
Identifiable assets	1,361.0				1,339.6				1,361.0	1,339.6	1,415.4
Operating Segments | Digital Imaging
Restructuring Charges:
Restructuring charges									2.0	3.2	2.7
Net sales:
Net Sales	110.9	98.5	99.4	89.9	102.1	95.7	90.8	90.4	398.7	379.0	403.6
Operating income:
Total operating income	15.3	11.7	10.7	8.2	11.5	10.4	8.8	9.3	45.9	40.0	37.1
Depreciation and amortization:
Depreciation and amortization:									26.2	26.1	29.6
Capital expenditures:
Capital expenditures:									12.5	9.2	10.3
Identifiable assets:
Identifiable assets	671.1				634.9				671.1	634.9	708.4
Operating Segments | Aerospace and Defense Electronics
Restructuring Charges:
Restructuring charges									4.6	1.2	0.9
Net sales:
Net Sales	151.8	153.5	158.0	152.6	153.9	151.3	147.0	141.2	615.9	593.4	603.0
Operating income:
Total operating income	28.5	31.5	28.0	24.1	21.3	23.5	20.6	19.4	112.1	84.8	88.3
Depreciation and amortization:
Depreciation and amortization:									14.4	15.0	15.9
Capital expenditures:
Capital expenditures:									12.6	9.1	8.8
Identifiable assets:
Identifiable assets	449.4				451.6				449.4	451.6	462.5
Operating Segments | Engineered Systems
Restructuring Charges:
Restructuring charges									0.1	0.1	(0.2)
Net sales:
Net Sales	65.6	66.5	62.2	64.3	77.7	65.2	68.6	63.1	258.6	274.6	271.9
Operating income:
Total operating income	9.9	8.6	5.6	8.0	8.7	5.9	4.8	6.7	32.1	26.1	31.4
Depreciation and amortization:
Depreciation and amortization:									4.1	3.5	3.7
Capital expenditures:
Capital expenditures:									5.9	5.7	4.3
Identifiable assets:
Identifiable assets	93.9				92.2				93.9	92.2	84.9
Corporate
Operating income:
Total operating income	(13.4)	$ (11.1)	$ (10.8)	$ (10.8)	(10.1)	$ (8.9)	$ (11.0)	$ (10.2)
Corporate expense									(46.1)	(40.2)	(43.9)
Depreciation and amortization:
Depreciation and amortization:									5.3	4.5	4.0
Capital expenditures:
Capital expenditures:									5.7	2.1	3.1
Identifiable assets:
Identifiable assets	199.0				198.8				199.0	198.8	191.0
Prepaid pension assets	$ 88.5				$ 111.0				$ 88.5	$ 111.0	$ 86.3