Business Segments (Product Lines) (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
Summary of the segments sales by product line
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
Instrumentation
Summary of the segments sales by product line
Net Sales									876.7	1,051.1	1,115.5
Environmental Instrumentation | Instrumentation
Summary of the segments sales by product line
Net Sales									270.1	268.7	268.4
Marine Instrumentation | Instrumentation
Summary of the segments sales by product line
Net Sales									418.7	614.0	654.8
Test and Measurement Instrumentation | Instrumentation
Summary of the segments sales by product line
Net Sales									$ 187.9	$ 168.4	$ 192.3