Business Segments (Business Segments) (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		Jan. 03, 2016		Sep. 27, 2015	[1]	Jun. 28, 2015	[1]	Mar. 29, 2015	[1]	Dec. 28, 2014		Sep. 28, 2014	[2]	Jun. 29, 2014	[2]	Mar. 30, 2014	[2]	Jan. 03, 2016	Dec. 28, 2014	Dec. 29, 2013
Sales:
Sales by country:		$ 600.0	[1]	$ 555.4		$ 577.7		$ 565.0		$ 622.3	[2]	$ 601.1		$ 597.1		$ 573.5		$ 2,298.1	$ 2,394.0	$ 2,338.6
Income before taxes:
Total segment operating profit																		281.7	294.5	240.3
Corporate expense																		(40.2)	(43.9)	(37.6)
Interest and debt expense, net																		(23.9)	(19.0)	(20.4)
Other income, net																		0.4	6.6	4.1
Income before income taxes																		258.2	282.1	224.0
Depreciation and amortization:
Depreciation and amortization:																		90.3	94.3	91.1
Capital expenditures:
Capital expenditures:																		47.0	43.5	72.6
Identifiable assets:
Identifiable assets:		2,718.5								2,862.2								2,718.5	2,862.2	2,751.1
Prepaid pension assets		111.0								86.3								111.0	86.3
Instrumentation
Sales:
Sales by country:																		1,051.1	1,115.5	1,022.8
Income before taxes:
Total segment operating profit																		171.0	181.6	162.0
Depreciation and amortization:
Depreciation and amortization:																		41.2	41.1	38.2
Capital expenditures:
Capital expenditures:																		20.9	17.0	22.0
Identifiable assets:
Identifiable assets:		1,339.6								1,415.4								1,339.6	1,415.4	1,204.5
Digital Imaging
Sales:
Sales by country:																		379.0	403.6	414.8
Income before taxes:
Total segment operating profit																		40.0	37.1	28.2
Depreciation and amortization:
Depreciation and amortization:																		26.1	29.6	30.3
Capital expenditures:
Capital expenditures:																		9.2	10.3	20.2
Identifiable assets:
Identifiable assets:		634.9								708.4								634.9	708.4	745.1
Aerospace and Defense Electronics
Sales:
Sales by country:																		593.4	603.0	625.1
Income before taxes:
Total segment operating profit																		84.8	88.3	65.7
Depreciation and amortization:
Depreciation and amortization:																		15.0	15.9	16.5
Capital expenditures:
Capital expenditures:																		9.1	8.8	15.3
Identifiable assets:
Identifiable assets:		451.6								462.5								451.6	462.5	436.9
Engineered Systems
Sales:
Sales by country:																		274.6	271.9	275.9
Income before taxes:
Total segment operating profit																		26.1	31.4	22.0
Depreciation and amortization:
Depreciation and amortization:																		3.5	3.7	4.2
Capital expenditures:
Capital expenditures:																		5.7	4.3	3.6
Identifiable assets:
Identifiable assets:		92.2								84.9								92.2	84.9	92.3
Corporate
Depreciation and amortization:
Depreciation and amortization:																		4.5	4.0	1.9
Capital expenditures:
Capital expenditures:																		2.1	3.1	11.5
Identifiable assets:
Identifiable assets:	[3]	200.2								191.0								200.2	191.0	272.3
Prepaid pension assets		$ 77.2								$ 86.3								$ 77.2	$ 86.3	$ 222.0

[1] Fiscal year 2015 was a 371 year, each quarter contained 91 weeks except the fourth quarter which contained 98 weeks.

[2] Fiscal year 2014 was a P364D-week year, each quarter contained P91D weeks.

[3] (a) The amount for 2015, 2014 and 2013 includes $77.2 million, $86.3 million and $222.0 million prepaid pension asset, respectively.