Segment Information (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2017 USD ($) product_line	Oct. 02, 2016 USD ($)	Oct. 01, 2017 USD ($) segment product_line	Oct. 02, 2016 USD ($)
Revenue from External Customer [Line Items]
Number of reportable segments | segment			4
Restructuring costs | $	$ 2.6	$ 3.1	$ 6.1	$ 15.3
Restructuring reserve included in other current liabilities | $	$ 0.9		$ 0.9
Aerospace and Defense Electronics
Revenue from External Customer [Line Items]
Number of product lines	1		1
Engineered Systems
Revenue from External Customer [Line Items]
Number of product lines	1		1
Instrumentation
Revenue from External Customer [Line Items]
Number of product lines	3		3
Digital Imaging
Revenue from External Customer [Line Items]
Number of product lines	1		1