Segment Information (Sales) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2017	Oct. 02, 2016	Oct. 01, 2017	Oct. 02, 2016
Revenue from External Customer [Line Items]
Net sales	$ 662.2	$ 526.8	$ 1,899.4	$ 1,597.0
Operating Segments | Instrumentation
Revenue from External Customer [Line Items]
Net sales	232.5	208.3	699.1	652.1
Operating Segments | Instrumentation | Marine Instrumentation
Revenue from External Customer [Line Items]
Net sales	101.8	97.6	318.3	314.3
Operating Segments | Instrumentation | Environmental Instrumentation
Revenue from External Customer [Line Items]
Net sales	77.7	63.8	230.2	200.4
Operating Segments | Instrumentation | Test and Measurement Instrumentation
Revenue from External Customer [Line Items]
Net sales	$ 53.0	$ 46.9	$ 150.6	$ 137.4